Question

How do you solve using the quadratic formula `x^2 + x - 42 = 0`?

Answer 1

x=6, -7

Compare the given equation with `ax^2+bx+c=0` and determine a=1, b=1 and c= -42. Plug these values in the quadratic formula x= `(-b+-sqrt(b^2-4ac))/(2a)`

x= `(-1+-sqrt(1+168))/2`

= `(-1+-13)/2`

x=6, -7

Answer 2

There is another way. Use the new AC Method.
y = x^2 + x - 42.
Compose factor pairs of c = -42. Proceed: (-1, 42)(-2, 21)(-3, 14)(-6, 7).
This last sum is -6 + 7 = 1 = b. Then, the 2 real roots are: 6 and -7.