Question

6. (a) If p2 +q2 = 252 and p+q = 16, evaluate pq. late yu​

Answer 1

p+q=16

p²+q²=252

or, (p+q)²-2pq=252

or, (16)²-2pq=252

or, 256-2pq=252

or, -2pq=252-256

or, -2pq=-4

or, pq=4/2

or, pq=2

Answer 2

$\text{Given that}, \\\\p^2 +q^2 =252 , ~ p+ q =16\\\\\text{Now},\\(p+q)^2 = p^2 +q^2 +2pq \\\\ \implies 2pq = (p+q)^2 -(p^2 +q^2)\\ \\ \implies pq = \dfrac{(p+q)^2 -(p^2 +q^2)}{2}= \dfrac{16^2 - 252}{2} = \dfrac{256-252}{2} =\dfrac 42 =2$