SOLUTION: 2.how can i solve this system of equation by substitution -7x-2y=-13,x-2y=11? pls help me..

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Question 325289: 2.how can i solve this system of equation by substitution -7x-2y=-13,x-2y=11?
pls help me..
Found 2 solutions by jim_thompson5910, tinbar:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
x-2y=11 Start with the second equation.


x=2y%2B11 Add 2y to both sides.


-7x-2y=-13 Move back to the first equation.


-7%282y%2B11%29-2y=-13 Plug in x=2y%2B11


-14y-77-2y=-13 Distribute.


-16y-77=-13 Combine like terms on the left side.


-16y=-13%2B77 Add 77 to both sides.


-16y=64 Combine like terms on the right side.


y=%2864%29%2F%28-16%29 Divide both sides by -16 to isolate y.


y=-4 Reduce.


x=2y%2B11 Go back to the previously isolated equation.


x=2%28-4%29%2B11 Plug in y=-4


x=-8%2B11 Multiply


x=3 Add


So the solutions are x=3 and y=-4 which form the ordered pair (3,-4)

Answer by tinbar(133) About Me  (Show Source):
You can put this solution on YOUR website!
from the second statement u can isolate x to get x=11+2y. we will use the right side of this equation to sub into the first equation's x variable.
-7(11+2y)-2y=-13
-77-14y-2y = -13
-16y=64
y=-4
use this value into either equation 1 or 2 to get x. using equation 2 will be easier so since we already know x=11+2y, x=11+2(-4), x=11-8, x=3
check:
-7(3)-2(-4)=-21+8 = -13, as expected
and 3-2(-4)=3+8=11, as expected
therefore x=3, y=-4