### Question

**If p − q = 6 and p**^{2} + q^{2} = 116 , what is the value of pq ?

^{2}+ q

^{2}= 116 , what is the value of pq ?

A. 50

B. 40

C. 30

D. 20

#### Answer: B. 40

**Solution:**

{reference: basic algebraic formulas}

(p − q)^{2} = p^{2} − 2pq + q^{2}

⇒ 62 = 116 − 2pq

⇒ 36 = 116 − 2pq

⇒ 2pq = 80

⇒ **pq = 40**

**Similar Question:**

**If (a^2 + b^2) = 10 and ab = 3; find a + b = ?**