Question

Solve -7x-8y=9, -4x 9y=-22

Answer 1

To solve the system of equations -7x - 8y = 9 and -4x + 9y = -22 using the method of substitution, we first solve one equation for one variable and then substitute that expression into the other equation. By doing so, we find that x = 2/7 and y = -190/41.

Step-by-step explanation:

To solve the system of equations -7x - 8y = 9 and -4x + 9y = -22, we can use the method of substitution. We start by solving one equation for one variable and then substituting that expression into the other equation. Let's solve the first equation for x:

-7x - 8y = 9

-7x = 9 + 8y

x = (9 + 8y)/(-7)

Now we substitute this expression for x into the second equation and solve for y:

-4((9 + 8y)/(-7)) + 9y = -22

Simplifying, we get:

36 + 32y + 9y = -154

41y = -190

y = -190/41

Substituting the value of y back into the first equation, we can solve for x:

x = (9 + 8(-190/41))/(-7)

After simplifying, we find:

x = 2/7

So the solution to the system of equations is x = 2/7 and y = -190/41.

Answer 2

-7x - 8y = 9 . . . . . (1)
-4x + 9y = -22 . . . . . (2)

(1) x -4 => 28x + 32y = -36 . . . (3)
(2) x -7 => 28x - 63y = 154 . . . (4)

(3) - (4) => 95y = -190 => y = -190/95 = -2
substituting for y = 2 in (1), we have
-7x - 8(-2) = 9 => -7x + 16 = 9 => -7x = 9 - 16 = -7 => x = -7/-7 = 1

Therefore, x = 1 and y = -2.