SOLUTION: Solve for x and y by deriving an expression for y from the second equation, and substituting it back into the first equation.
−5x−7y=9
6x+9y=-9
Algebra.Com
Question 734832: Solve for x and y by deriving an expression for y from the second equation, and substituting it back into the first equation.
−5x−7y=9
6x+9y=-9
Answer by checkley79(3341) (Show Source): You can put this solution on YOUR website!
−5x−7y=9
6x+9y=-9
9y=-6x-9
y=(-6x-9)/9
-5x-7(-6x-9)/9=-9
-5x+(42x+63)/9=-9
(-5x*9+42x+63)/9=-9
(-45x+42x+63)=-9*9
-3x+63=-81
-3x=-81-63
-3x=-144
x=-144/-3
x=48 ans.
y=(-6*48-9)/9
y=(-288-9)/9
y=-297/9
y=33 ans.
Proof:
5*48-7*33=9
240-231=9
9=9
RELATED QUESTIONS
Solve for x and y by deriving an expression for y from the second equation, and... (answered by Alan3354)
Find the value of y for the given value of x by first substituting the value of x into... (answered by rfer,dyakobovitch)
If the system of equations given below is solved using the substitution method, what is... (answered by vleith)
i can't under stand if 3x+2y = -17
2x-5y = 14 the what is the... (answered by rfer)
6x-9y=9; x=3
Find the value of y for the given value of x by first solving for y and... (answered by ankor@dixie-net.com)
Find the value of y for the given value of x by first substituting the value of x into... (answered by rfer)
Find the value of y for the given value of x by first substituting the value of x into... (answered by dyakobovitch)
Solving using the substitution method:
8x - 5y = -47
4x + 3y = -7
I got some help (answered by scott8148,checkley77)
Solve the following systems by substitution. Substitute the expression in the second... (answered by robertb)