Question

If a-b=9 ab=10 (1) a²+b²=? (2) (a+b)²=?

Answer 1

Answer:

(1) 101. 2) 121

Explanation:

we know by identity

(a-b)²= a²+b²-2ab

then ,

(a-b)²+ 2ab= a²+b²

a²+b²=9² +2×10 (as ab=10 and a-b = 9)

=81 + 20

= 101

(2) we know by identity

(a+b)²= a²+b² +2ab

= 101 +2×10

=121