Question

If a3 - b3 = 36, a - b = 3, then ab = what? ​

Answer 1

ANSWER

$a {}^{3} - b {}^{3} = 36 \\ = > (a - b)(a {}^{2} + b {}^{2} + ab) = 36 \\ = > (a {}^{2} + b {}^{2} + ab) = 12 \\ = > a {}^{2} + b {}^{2} = 12 - ab$

now ....a-b=3

now ...a²+b²=(a-b)²+2ab

==>12-ab=3²+2ab

=>12-9=3ab

=>>>>>ab=1