Question

Find all the zeros of the quadratic polynomial 5x² + 8x - 4 = 0.

Answer 1

Let f(x) = 5x² + 8x - 4 and α and β be its zeroes

Here a = 5, b = 8 and c = -4

5x² + 8x - 4 = 0

5x² + 10x - 2x - 4 = 0

5x(x + 2) - 2(x + 2) = 0

(x + 2)(5x - 2) = 0

x + 2 = 0 or 5x - 2 = 0

x = -2 or x= 2/5

So, the zeroes are α = -2 and β = 2/5