SOLUTION: if 5x - 3y = 7 and -3x - 5y = 23 what is the value of x? my answer choices are: A. (-1,-4) B. (-4,-1) C. -4 D. -1 I tried using substitution but I do not get any of the

Algebra ->  Linear-equations -> SOLUTION: if 5x - 3y = 7 and -3x - 5y = 23 what is the value of x? my answer choices are: A. (-1,-4) B. (-4,-1) C. -4 D. -1 I tried using substitution but I do not get any of the       Log On


   

Question 919866: if 5x - 3y = 7 and -3x - 5y = 23 what is the value of x?
my answer choices are:
A. (-1,-4)
B. (-4,-1)
C. -4
D. -1
I tried using substitution but I do not get any of the above answers so I am stuck.
Found 2 solutions by richard1234, richwmiller:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
If (x,y) = (-1, -4), you have 5(-1) - 3(-4) = 7 and -3(-1) - 5(-4) = 23, both of which are true statements. So x = -1.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
+system%28+%0D%0A++++5%5Cx+%2B+-3%5Cy+=+7%2C%0D%0A++++-3%5Cx+%2B+-5%5Cy+=+23+%29%0D%0A++We'll use substitution. After moving -3*y to the right, we get:
5%2Ax+=+7+-+-3%2Ay, or x+=+7%2F5+-+-3%2Ay%2F5. Substitute that
into another equation:
-3%2A%287%2F5+-+-3%2Ay%2F5%29+%2B+-5%5Cy+=+23 and simplify: So, we know that y=-4. Since x+=+7%2F5+-+-3%2Ay%2F5, x=-1.

Answer: system%28+x=-1%2C+y=-4+%29.