If a−b=3 and a3 - b3 =117 ,then ab = _________
90
9
10
27
Given a−b=3
Cubing both sides, we get:
a3−b3−3ab(a−b)=27
Substituting the values of (a3−b3=117) and (a−b=3)
⇒117−3ab(3)=27
−9ab=−90
ab=10
If A+B=5 and AB=6. Find A3+B3.
If a3+b3=27 and a2+b2−ab=9, then a+b=___