Question

The quadratic equation x^2 + 3x + 50 = 0 has roots r and s. Find a quadratic equation whose roots are r^2 and s^2.

Answer 1

x^2 + 91x + 2500

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x^2 + 3x + 50

(x-r)(x-s)

-> x^2-(r+s)x+rs

rs = 50, r + s = -3

-> (rs)^2 = 2500

(r+s)^2 = 9

-> r^2 + 2rs + s^2 = 9

-> r^2 + 2(50) + s^2 = 9

-> r^2 + s^2 + 100 = 9

-> r^2 + s^2 = -91

(x-r^2)(x-s^2)

-> x^2-(r^2+s^2)x+(rs)^2

-> x^2 - (-91)x + 2500

x^2 + 91x + 2500