Question

Using the Quadratic Formula, which of the following is the solution to the quadratic equation x2 - 3x - 28 = 0?


A.x = -7, -4


B.x = 7, 4


C.x = -7, 4


D.x = 7, -4

Answer 1

The answer is (x+7)(x-4)

hence, the solution should be C

Answer 2

x = [ -)-3)  +/- sqrt((-3)^2 - 4*1*-28) ] / 2

=  (3 + sqrt 121) / 2   and (3 - sqrt 121) / 2

= 3/2 + 11/2  and 3/2 - 11/

= (1.5 + 5.5)   and 1.5 - 5.5

Answer is 7, -4