Question

Solve this equation 9x−4y=−7

7x−12y=39
A) x= 25 ,y=4
B) x=−3,y=2​
C) x=1,y=−5
D) x=2,y=−3

Answer 1

To solve the system of equations, multiply the first equation by 7 and the second equation by 9 to eliminate the x variable. Then subtract the second equation from the first equation to eliminate the x variable. Next, divide both sides of the equation by 80 to solve for y. Finally, substitute the value of y back into either of the original equations to solve for x.

Step-by-step explanation:

To solve the system of equations:

9x - 4y = -7

7x - 12y = 39

1. Multiply the first equation by 7 and the second equation by 9 to eliminate the x variable: 63x - 28y = -49 and 63x - 108y = 351.
2. Subtract the second equation from the first equation to eliminate the x variable: 80y = 400.
3. Divide both sides of the equation by 80 to solve for y: y = 5.
4. Substitute the value of y back into either of the original equations to solve for x: 9x - 4(5) = -7. Simplify the equation: 9x - 20 = -7. Add 20 to both sides: 9x = 13. Finally, divide both sides by 9 to solve for x: x = 13/9.

Therefore, the solution to the system of equations is:

x = 13/9 and y = 5.