Question

Solve by addition or substitution.
4x-3y=24
8x-4y=56
Can someone tell me step by step how to do this I need to know for my test 2marrow.

Answer 1

solve for x in 1st equation. x=(24+3y)/4, then input x on 2nd eq. 8(24+3y)/4-4y=56.
then solve for Y and find its value. then input Y on fisrt equation and find X. hope it helps

Answer 2

\[4x-3y=24[1]\]
\[8x-4y=56[2]\]
\[[1]\times 2\]
\[2(4x-3y)=2(24)\]
\[8x-6y=48[3]\]
\[[2]-[3]\]
\[(8x-4y)-(8x-6y)=(56)-(48)\]
\[-4y--6y=8\]
\[-4y+6y=8\]
\[2y=8\]
\[y=4\]
To find x, sub in the y-value into one the three equations given by me above. (ie. [1], [2] or [3])

Answer 3

what did you do when you got to (8x-4y)-(8x-6y)=(56)-(48) dont understand what u did to get ur answers

Answer 4

I told you in that step I subtracted equation 3 from equation 2.

Answer 5

[3]-[2]

Answer 6

ok got it u canceled out 8x

Answer 7

[2]-[3] sorry.

Answer 8

Yeah. You have to get rid of a variable.

Answer 9

That's the main thing about these. Getting rid of variables until you have one left.

Answer 10

yeah i just didnt get it but now i see u canceled out 8x and it=-4y- -6

Answer 11

Yep.

Answer 12

Remember to find x.

Answer 13

could you help me find x cause im confused

Answer 14

I told you at the end.

Answer 15

That's the most easiest part when you have one variable and you're finding the other.

Answer 16

yeah that means x cud be 3 different numbers.

Answer 17

no.

Answer 18

Try testing it for all three equations. You get the same x-value.

Answer 19

no matter what happens, you get the same x-value...

Answer 20

so how would I multiply 4 by 24?

Answer 21

by using a calculator or getting better at multiplication. If you want to get better at multiplication I suggest you go back to grade 1.

Answer 22

I ment is that what u want me to do for each one multiply it by the 24,56 and 48?

Answer 23

no Where'd you get that from. The numbers in the brackets are just to tell you the number of equations I used.
For example,
[1] means the first equation, [2] means the second equation and [3] is the 3rd equation. What don't you get?

Answer 24

Ok x=9 thanks.

Answer 25

You're welcome.