Question

Use Cramer's Rule to solve the following system equations. Write each answer in simplest form.

-5x + 9y = -9

5x - 8y = 4

Write the three relevant determinants (D, Dx, Dy):
The solution to the system is x = and y =

Answer 1

The system of equations is:

-5x + 9y = -9

5x - 8y = 4

The determinant of the coefficients is:

D = |-5 9|

| 5 -8|

D = (-5)(-8) - (9)(5) = 40 - 45 = -5

The determinant of x is found by replacing the x-coefficients with the constants:

Dx = |-9 9|

| 4 -8|

Dx = (-9)(-8) - (9)(4) = 72 - 36 = 36

The determinant of y is found by replacing the y-coefficients with the constants:

Dy = |-5 -9|

| 5 4|

Dy = (-5)(4) - (-9)(5) = -20 + 45 = 25

Using Cramer's Rule:

x = Dx/D = 36/-5 = -7.2

y = Dy/D = 25/-5 = -5

Therefore, the solution to the system is x = -7.2 and y = -5.

Hope this helps!