Question:
Factorize:
$2 x^{2}+11 x-21$
Solution:
We have:
$2 x^{2}+11 x-21$
We have to split 11 into two numbers such that their sum is 11 and their product is $(-42)$, i.e., $2 \times(-21)$.
Clearly, $14+(-3)=11$ and $14 \times(-3)=-42$.
$\therefore 2 x^{2}+11 x-21=2 x^{2}+14 x-3 x-21$
$=2 x(x+7)-3(x+7)$
$=(x+7)(2 x-3)$
Click here to get exam-ready with eSaral
For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.