Question

If p & q are roots of equati 2x^2-5x+7=0 then the value of (p^2+q^2)

Answer 1

Sum of roots = -B/A

Product of roots = C/A

A = 2. B = 5. C = 7.

As the roots are (a) and (b),

a + b = -3/2. ab = 4/2 = 2

(a + b)^2 = a^2 + b^2 + 2ab

-> a^2 + b^2 = (a + b)^2 - 2ab …(remember this)

-> a^2 + b^2 = (-3/2)^2 - 2(2)

-> a^2 + b^2 = 9/4 - 4

-> a^2 + b^2 = -7/4