Question

need help with solving simultaneous equations by graphing

Answer 1

just plot the lines. where the lines meet, that point is the solution.

Answer 2

but they are giving me funny instructions

Answer 3

like what?

Answer 4

A: Y=3x-2
b: y=2x+3

Answer 5

the point I came up with was (6,0) which is wrong

Answer 6

can you help me to do it and not just give me the answer

Answer 7

x=5, y=13

Answer 8

how

Answer 9

wait

Answer 10

for eq 1, find three points that fit the equation. how? just plot random values for x, and find y. But use small numbers; starting from 0 or 1 always helps.
do the same for second.
just plot those lines based on those oints.
now, find where the lines meet. if needed, just prolong the line straight.
Where they meet, find the corresponding value of x and y.
that is the solution.

Answer 11

y=13? my graoh on the paper only goes to 6. 12 if u count the negatives

Answer 12

if ur graph does not have upto 13, there are two options
1. only represent one quarter,( where both x and y are positive) in ur graph.
2. decrease the units u are using in ur graph

Answer 13

I don't exactly understand what you are saying. :/
this is what they said to do in my video and why I am stuck.

Answer 14

so just pick random numbers from the air?

Answer 15

which part don't u understand?

Answer 16

seems illogical

Answer 17

no it does not. i mean, that is what a line is. it can have any values of x, and as long as u calculate y from it, the point (x,y) is within the line.
Besides u need some way to represent the line in the graph. how else would u represent a line other than plotting points and joining them? and how do u get the points? just find out some points that fit the line, and plot them straightly.

Answer 18

you lost me at any values of x
you should know I have ADHD so trying to teach me this will be a little hard

Answer 19

so lets start from the begining.

Answer 20

ok

Answer 21

If you are given an equation such as Y=3x-2
The x value can be anything on the graph as it is a straight line and will go on forever and ever and ever.
So to plot the straight line between specific points, we substitute numbers for x (because it can go from -infinite to infinite

so let us start with substituting x=0, x=1, x=2

when x =0
y=3(0)-2

continue this with values of x, then do the same with your other equation. connect the points to form two straight lines, and they will intersect at specific points, that is your solution

Answer 22

you are given two equations. your task is to find a point, which means a value for x, and a value for y, that both satisfies the given equations, and u need to do it by plotting the graphs of the two equations given. clear till here?

Answer 23

to plot a line, you need only 2 points.
to find two points:

pick x=0, and find y
pick y=1 and find y
plot those points and draw a line through them

Answer 24

@mjbmanny yes I got that part!

Answer 25

well, that is true phi, but in case of some lines that don,t pass through x=0, or y=0, then picking 0 and 1 can't be best.

Answer 26

plot those points and draw a line through them, and make the line as long as necessary ...

Answer 27

allright, josh, now u got to find some points that satisfy the equations. why? because u need to plot the equation on the graph as a line.
and , as phi just said, picking two points for each line is enough.But, to be really certain, it is better to find out three points.

Answer 28

phi im n ot all that bright u know if I don't Instantly know what 5x5 is it takes me 60 sec to figure it out

Answer 29

3?

Answer 30

Here is what the first line looks like

Answer 31

Y = 2/1x -2

Answer 32

in fraction form

Answer 33

allright, josh,
now how do u find the points that i mentioned before?
u see, every point in a line satisfies the equation representing the line. which means, if u put on x, and u get some y. then if u replace the values of variables x and y in the equation, two sides of the eqaution become equal.

so, picking points in a line is not awkard at all.

Answer 34

but don't we only pick 1 number?

Answer 35

for all the equations

Answer 36

u pick one number and then put that number in place of the variable u picked for. then calculate the value of another varible, find it out. then the nuber u picked for first variable, and the answe u got after placing the number in place of the variable u picked for, that constitutes a point. U need two such points for each line to be able to draw a line.

Answer 37

I thought u said 3

Answer 38

yes, 3 is better. but two is enough

Answer 39

what about the 3rd point

Answer 40

i said that because in some cases, u need to elongate the lines a lot to be able to meet the two lines. So, taking 3 points reduces the chance of error. how? well if u have three points u are more likely to extend the line straight( which is most important).

the point is , u need at least two points to draw line. but u can as well pick 3,4,5, or whatever points u want if u have time to waste.

Answer 41

so how do I know when I have picked the right numbers

Answer 42

just pick two points as a rule,. two is enough. think it this way. what is a line? its a series of points. so, how many points would u need to represent a line? just two. because remaining points can be found out just by elongating the line straight. But can u say something about a line by using just one point? no. u need at least two. if u are not understanding this forget three and why 3 is better, just think two.

Answer 43

how do I know when I have picked the correct points

Answer 44

u see every point is correct if it fits the equation. which is to say for suppose an example equation
x+3y=6,
i can pick 100, for the value of x,and put x=100, in the equation. then the corresponding y would be -(93/6). this point is also a correct point, because it is a point in the line. i got -(93/6) by putting x =100. Since I got this from the equation itself, there is no doubt it fits the equation.

But, as u discovered ur graph doesnot have enough space for 100. and the calculations are also more difficult.
so, lets pick a smaller value of x, say x=0. then the corresponding value of y would be y=6/3=2. And for another point of the line lets pick x=1( and this shows why sometimes this can be tricky). so the corresponding value of y woudl be (5/3). but as it is difficult to plot a decimal, lets pick another x. how about 3?
say x=3. then y=1. so the two points of the line are (0,2) and (3, 1).
Now, u got to do the same for both the equations given to you itn the above question. and plot the points for each line; join the corresponding points of a line, and see where two lines cross( if necessary, extend the lines ,straightly!; and the value of x, and y u get of the point of crossing is ur answer. and that is the point that satisfies both equations.

Answer 45

what is x+3y=6 what format is that and how do I change it

Answer 46

how did u get 100 from the equation

Answer 47

nope nevermind u lost me again how did u get 93/6

Answer 48

it was an example equation. just as the two you posted in ur question.

I picked 100 from random to illustrate that theoretically, u can take any value of x. but it is more practical to take smaller values

Answer 49

ok?

Answer 50

lets get back to x+3y=6.

Answer 51

so, i need two points that fit this equation got it?

Answer 52

yes but let me see if I can do this ok?

Answer 53

yes, i thinkk u can understand better if u practice right here.

Answer 54

X-Y=2
and X+3Y=6
are my two equations

Answer 55

ok

Answer 56

I need fix the equations right?

Answer 57

yes, u need to find wo points from both these equations. lets start with first; x-y=2

Answer 58

so Y=x-2 right

Answer 59

absolutely

Answer 60

so x=1 to start and I need another point from this equation?

Answer 61

yes. replace the x by 1, and see what y turns out to be.

Answer 62

that would make y 1

Answer 63

y = 3x - 2
slope is 3
y intercept is (0,-2)
x intercept is (2/3,0)
now plot your points and draw a line to connect them

y = 2x + 3
slope is 2
y intercept is (0,3)
x intercept is (-3/2,0) for graphing purposes x int is (-1 1/2,0)
plot your points and connect them with a line.

where you lines cross each other is your solution

Answer 64

no, it would make y -1.

Answer 65

oh ok so it would not fit

Answer 66

why not? the first point of ur equation y=x-2, is (1,-1). now find similar another using different x

Answer 67

pick any from 0, 2, 3...

Answer 68

?
how did u get that

Answer 69

what? 0, 2, 3.....

Answer 70

yes

Answer 71

well u can guess anything( thoretically, u can even include fractioins or negative integerts). But, i picked 0, 2, 3 because; they are small and positive, which will help me by makint the calculation short. and why i left 1? because i already used it. if i take 1 again, i would get the same point, and i wont have the necessary two points. all right, u pick anyhting u want.

Answer 72

3y=x+6

Answer 73

I need a negative integer

Answer 74

so -2

Answer 75

so y is 4

Answer 76

soooo...

Answer 77

-2,4

Answer 78

its a straight line

Answer 79

yes?

Answer 80

@mjbmanny

Answer 81

josh, there was some technical problem. now its fine.

Answer 82

ok

Answer 83

its a really long thing so a mod was probly alerted cause I couldn't either

Answer 84

2x + 3 = 3x - 2
2x - 3x = -2 -3
-x = -5
x = 5

y = 2x + 3
y = 2(5) + 3
y = 10 + 3
y = 13

your lines should cross at (5,13)

Answer 85

thanks for no giving me the answer

Answer 86

all that work for nothing

Answer 87

first, u got to calculate another point for the earlier equation. u only got one. u need two. lets do that and move to another equation. for 1st equation, u used x=1,and got y=-1, and the point was thus(1,-1). now u need to find another point. for ur first equation y=x-2.

Answer 88

so the next one is Y=2x+-2
and y=1/3x+5

Answer 89

please don't post the answer

Answer 90

josh, i couldnot understand what u posted. lets think this as clearly as the sunlight.

Answer 91

Y=2x+-2
and y=1/3x+5

Answer 92

and what value of x u chose? are u posting two new equations?

Answer 93

yes

Answer 94

why? u arent done with earlier ones.

Answer 95

texas just posted the whole equation

Answer 96

if u still insist, lets start afresh withe these two. the important thing is u understand what u are doing.

texas solved the equaions you posted in the begining algebrically,a nd got the answer. the same way I did to produce the answer earlier.
we are trying to solve equations graphically. arent we?

Answer 97

y=2x+-2
2x=
not 0 or 1 that might not make any sense so lets try 2