Question

Find the values of x if p + 7 = 0, q – 12 = 0 and x² + px + q = 0,

Answer 1

p + 7 = 0, then p = – 7
and q – 12 = 0, then q = 12
Substituting the values of p and q in the given quadratic equation,
x² – 7x + 12 = 0
⇒ x² – 3x – 4x + 12 = 0
⇒ x(x – 3) – 4(x – 3) = 0
⇒ (x – 3) (x – 4) = 0
Either x – 3 = 0,
then x = 3
or
x – 4 = 0,
then x = 4
Hence x = 3, 4.