Question

Find an equation of the line containing the given point and with the given slope.
a.) (1,2), m=3
b) (0,-4), m=-2

Answer 1

write down what you know, starting with
y= mx+b

Answer 2

ok

Answer 3

ok y=mx+b
y=3x+
would it be the 2 even though the given point is (1,2)

Answer 4

pretty close. leave in the b
y= 3x+b

now "solve for b" using the (x,y) pair they gave you. that means the first step is to replace x and y with the numbers. and leave in the b

Answer 5

y=mx+b
y=3x+b
2=3(1)+b

Answer 6

now simplify 3(1) 3*1 is 3
so you have
2= 3+b

I would add -3 to both sides

Answer 7

-1=b

Answer 8

now you know m and b, so you can write down the equation of the line

Answer 9

so it would be: 2=3x-1

Answer 10

almost. try again

Answer 11

2=3x+-1

Answer 12

you start with the form
y= mx+b as the equation you want. Using all the info they give you, you figure out m and b. Replace m and b with the numbers, and that is the equation of the line

Answer 13

so y=3x+b
from there i plug in my given points
2=3(1)+b
from there i find b by adding -3 to both sides
-1=b
so my equation would be 2=3-1???????

Answer 14

you found m=3 (actually, they told you that) and you figured out b= -1

if you go back to the bottom of the previous post, you asked how to find the equation of a line if you know the slope (m) and the y-intercept (b). Look at that.
But 2=3-1??????? is not the equation of a line. It is a true equation 2 is 3-1, but there is no x and y. The equation of a line tells you how to find y when you are given x. you need a y and an x !

Answer 15

If it helps, after you know m=3 and b= -1. Erase everything from your brain and start with
y = mx+b

what is the equation of the line when m= 3 and b=-1 ?

Answer 16

y=3x-1?

Answer 17

yes. before you had 2=3x-1 which was close. but the 2 should be a y

notice that you started with y= mx+b and replace m with 3 (they told you that)
to get
y= 3x+b
then to figure out b, you used the fact that (1,2) is on the line, so it must be true that
2= 3(1)+b
and b must be, after solving, -1

next, you write down the important facts: m=3 and b= -1
and the form
y= mx+b

fill in for m and b and you get the answer
y= 3x -1

Answer 18

now try question (b)

Answer 19

(0,4), m=-2
y=mx+b
y=-2x+b
4=-2x(0) +b
4=0+b
so the answer is y=-2x + 4

Answer 20

that was supposed to say 4=-2(0) +b without the x in there

Answer 21

yes. notice that point (0,4) has 4 on the y-axis. 4 is the y-intercept so you could just write y= -2x + 4. But doing the way you did also works.