SOLUTION: I need to solve for x and y by using substitution. I am not sure of how to go about doing this problem. If someone could help I would appreciate it. The problem is: {y=8-3x

Question 240184: I need to solve for x and y by using substitution. I am not sure of how to go about doing this problem. If someone could help I would appreciate it. The problem is:
{y=8-3x
{2x-5y=11
I know that I need to multiply one problem to make the y's cancel but I am not sure.
Thanks
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
I need to solve for x and y by using substitution.
y = 8 - 3x
2x - 5y = 11
:
Note that y = (8-3x), substitute this for y in the 2nd equation
2x - 5(8-3x) = 11
Multiply what's inside the brackets, change the signs inside the brackets
2x - 40 + 15x = 11
2x + 15x = 11 + 40
17x = 51
x =
x = 3
:
Use the 1st equation to find y, substitute 3 for x
y = 8 - 3(3)
y = 8 - 9
y = -1
:
:
Check solutions by substitution in the 2nd equation
2x - 5y = 11
2(3) - 5(-1) = 11
6 + 5 = 11; confirms our solutions
;
:
you made the statement,"I know that I need to multiply one problem to make the y's cancel"
This is not so in the substitution method. You've got it mixed up with the elimination method.
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