Question

The roots of the equation x^2+bx+c=0 are −4 and 2. Find b and Find c

Answer 1

Since its roots are -4 and 2 and a = 1 [The coefficient of x^2] we know that x^2 + bx + c = (x - (-4)) (x-2)=(x+4)(x-2) = 0. Using the distributive property we get, x^2 + 2x - 8 = 0. By equating coefficients (common strategy for partial fractions and undetermined coefficient method of solving ODE), we get b = 2 and c = -8.

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