Question

if a+b=4 and a^2+b^2=7 then ab=?​

Answer 1

We know that;

(a+b)^2=a^2+b^2+2ab

According to the question

a+b=3 and a^2+b^2=7

put these values in the question

(3)^2=7+2ab

9–7=2ab

2/2=ab

1=ab