3. Solve the system using substitution.
y = -5x +9
15x + 3y = 27
a. (0,9)
b. (1,4)
c. No solution
d. Infinite solutions

D. Infinite solutions.

Step-by-step explanation:

Since they give us the equation for (y) we just implement that equation in place of (y) in the second equation

15x+3y=27 now becomes

15x+3(-5x+9)=27

Distribute the 3

15x-15x+27=27

15x and -15x cancel out

27=27

Infinite solutions since both sides are exactly equal.

Hope this helps! If you have any questions on how I got my answer feel free to ask. Stay safe!

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15