Question

pq-rs=7, pqrs=5, then p²q²-r²s²=?

Answer 1

Step-by-step explanation:

pq-rs=7, pqrs=5 , this is similar to

a - b = 7, ab = 5

so,

(a-b)² = a²+b²-2ab

(7)² = a²+b²-2(5)

49 = a²+b²-10

a²+b² = 59

now substitute,

(PQ)²- (rs)² = 59