Question

x³+ 4x³+ 11x - 21
Factorise completly​

Answer 1

Step-by-step explanation:

Solution :

The given expression is 2x2+11x-21.

Here, 2×(-21)=-42

We split 11 into two parts whose sum is 11 and product -42.

Clearly, 14+(-3)=11and14×(-3)=-42

∴2x2+11x-21=2x2+14x-3x-21

=2x(x+7)-3(x+7)

=(x+7)(2x-3)

Hence, (2x2+11x-21)=(x+7)(2x-3).