Geometry Help!!!! BC= x^2-18 CD= x+2?

Question

ok i know it then goes like x^2-18=x+2

but i dont what to do next, please explain to me how to combine the x's so i can finish the rest of my homework

Answer 1

BC = CD

BC = x^2 - 18

CD = x + 2

x^2 - 18 = x + 2

x^2 - x - 18 = 2

x^2 - x - 20 = 0

(x - 5)(x + 4) = 0

x - 5 = 0

x = 5

x + 4 = 0

x = -4

If x = 5:

BC = x^2 - 18 = 5^2 - 18 = 25 - 18 = 7

CD = x + 2 = 5 + 2 = 7

If x = -4:

BC = x^2 - 18 = (-4)^2 - 18 = 16 - 18 = -2

CD = x + 2 = -4 + 2 = -2

Answer 2

x^2 - 18 = x + 2

x^2 - x - 20 = 0

(x-5)(x+4)=0

x = 5 or -4