Question

Can you show me how to solve this equation using substitution
5y+4x=8
y=5x+10

Answer 1

yes. since it is stated that y = 5x +10; we can just substitute that value for "y" in the other equation and slove for "x"

Answer 2

5(5x + 10) + 4x = 8

25x + 50 + 4x = 8

29x + 50 = 8

29x = 8 - 50

29x = -42

x = -42/29

Answer 3

reduce if you can...

Answer 4

could you show me what I did wrong ill show you how I solved it

Answer 5

go right ahead :)

Answer 6

5y+4x=8
y=5x+10
5(5x+10)+4x=8
25x+50+4x=8
21x+50=8
21x=-42
x=-2
y=5(-20)+10
y=-10+10
y=0

Answer 7

That is what I did

Answer 8

And I was pretty sure that was the answer.

Answer 9

25x + 4x does NOT equal 21x

Answer 10

Oh sorry I made a typing misatke to y=5(-2)+10 should be the one line

Answer 11

Ithought you subtracted

Answer 12

nope; when it says 25 + 4, it actually means to add. That little (+) sign means add....

Answer 13

I know but I was taught that you did the opposite to get rid of it

Answer 14

why would you want to get rid of it? it is a vital part of the equation. Now, if it was on the OTHER side of the (=) sign, you would subtract it from BOTH sides to move it.

But, if it is on the SAME side, it is simply addition....

Does that make sense?

Answer 15

Look at your original question that you asked. Are you sure it doesn't say -4x in the problem you were given? 5y - 4x = 8?

Answer 16

Hold on let me check quick

Answer 17

If you want to move it to the othe side of the (=) sign we do this:

25 + 4 = 29

25 + 4 (-4) = 29 (-4)

25 = 29 - 4

But when it is on the same side, just add it together:

25 + 4 = 29

29 = 29

Answer 18

5y + 4x = 8
y + 5x = 10
it says ''solving a system of equations by substitution''

Answer 19

That is a different set of equations that what you give to begin with; please verify which one is correct please...

Answer 20

Im sorry

Answer 21

The last one is the correct one

Answer 22

ok :)

What does "y" equal then?:

y = 10 - 5x

substitute that "value" into the top equation to get:

5(10 - 5x) + 4x = 8
50 - 25x + 4x = 8
-25x + 4x = 8 -50
-21x = -42
x = -42/-21 = 2

Use this solid value of x=2 in the bottom equation to solve for "y"

y + 5(2) = 10
y + 10 = 10
y = 10 - 10

y = 0

x = 2

Answer 23

OK thanks im gonna look over this for a minute

Answer 24

Im sorry im kinda confussed I was taught in a different way and im trying to figure this all out

Answer 25

I got y=5x+10

Answer 26

you gave, for the bottom equation:

y + 5x = 10 ; to get "y" all by its little lonesome, we need to subtract (5x) from both sides to keep the same values...

y +5x -5x = 10 - 5x

y + 0 = 10 - 5x

y = 10 - 5x

Do you see it?

Answer 27

Not really im sorry

Answer 28

tell me where I am losing you then, let me know what is confusing you here. And then I can show you the right steps...

Answer 29

Can you tell me what the (=) sign means?

Answer 30

See for Y im somehow got -5x+10

Answer 31

-5x + 10 is correct, and it is the same thing as 10-5x

am i right or wrong?

Answer 32

Oh so then I did have it right?

Answer 33

you wrote, and I quote " I got y=5x+10" earlier.

If what you meant was "I got y= -5x+10" then yes, you are right...

Answer 34

Yeah thats what I meant im sorry I cant type today at all

Answer 35

:) paper and pencil is always easier when doing math

Answer 36

Yeah it is but thanks for showing me that now im gonna rework the problem and see if i get it right

Answer 37

so should the set up be 5(-5x+10)+4x=8

Answer 38

Yes

Answer 39

Ok I think im getting this down now

Answer 40

you are doing great :)

Answer 41

Thanks I have really been having a tough time this year

Answer 42

Does y = 2

Answer 43

and x=0

Answer 44

yes; y=0 and x=2.

To double check; plug those values into the original equations to see if they are true.

Answer 45

Ok thanks a lot :)