figure out what x cannot be:

Question

x²+11x+30 ⁄ x²+x-20 • x²-3x-4 ⁄ x²-4x-60

Answer 1

For rational expression, you cannot have a denominator equal to zero, it is undefined. So if you look at the denominators, factor them and solve. Those are the values x cannot be

x²+x-20 = (x+5)(x-4)

x+5=0

x=-5

x-4=0

x=4

x²-4x-60 = (x-10)(x+6)

x-10=0

x=10

x+6=0

x=-6