Question

If a^2-b^2= 21 and a^2+b^2=29, then what's ab?

Answer 1

Answer in attachment: Hope it helped.

Answer 2

a²-b²=21

a²+b²=29

a²+b²+a²-b²=21+29

2a²=50

a²=25

a=√25

a=±5


a²-b²=21

25-b²=21

b²=4

b=±5

a²+b²=(a+b)²-2ab

29=±7²-2ab

29=49-2ab

ab=10




so,ab =10

hope helped