Question

Factor the equation y = x2 + 4x - 21.​

Answer 1

The factored form of given equation y = x^2 + 4x - 21 is (x + 7)(x – 3)

Solution:

Given, equation is $y=x^{2}+4 x-21$

We have to factor the above equation

Now, take the expression $\mathrm{x}^{2}+4 \mathrm{x}-21$

$\rightarrow x^{2}+4 x-21$

"4x" can be splitted as (7 - 3)x

$\rightarrow x^{2}+(7-3) x-21$

"21" can rewritten as $7 \times 3$

$\rightarrow x^{2}+7 x-3 x-7 \times 3$

Taking "x" as common from first two terms and "3" as common from next two terms

$\rightarrow x(x+7)-3(x+7)$

Taking "x + 7" as common term,

$\rightarrow(x+7)(x-3)$

Hence, the factored form of given equation is y = ( x + 7 )( x – 3 )