Question

Use a quadratic equation to find two real numbers that satisfies the situation.
The sum of the two numbers is 12, and their product is -28.

Answer 1

Well,
two numbers x1 and x2 which have a sum = S and a product = P
are THE solutions of equation :
x^2 - Sx + P = 0
x^2 - 12x - 28 = 0
the quadratic formula gives:
∆ = (-12)^2 - 4*1*(-28) = 144+112 = 256 = 16^2
the solutions are therefore:
x1 and x2 = (12 +/- 16)/2 = 14 and - 2