Using the factorisation of xy2−xz2, evaluate the value of 6×32−6×22.
30
xy2−xz2
=x(y2−z2) (taking x common)
=x(y+z)(y−z)
[∵a2−b2=(a+b)(a−b)]
Comparing 6×32−6×22 with the above, we must have,
6×32−6×22
=6(3+2)(3−2)
=(6)(5)(1)=30