Question

Which of the following quadratic equations can be solved by grouping?(1 point)
Responses

x^(2)+8x−22=0

x squared plus 8 x minus 22 equals 0

x^(2)−4x−8=0

x squared minus 4 x minus 8 equals 0

x^(2)+10x+21=0

x squared plus 10 x plus 21 equals 0

x^(2)−12x+18=0

x squared minus 12 x plus 18 equals 0

Answer 1

x^2 + 10x + 21 = 0.

Reason: 3 + 7 = 10 and 3·7 = 21, so
x^2 + 10x + 21 = x^2 + 3x + 7x + 21 = x(x+3) + 7(x+3) = (x+3)(x+7).