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 * 3`

`\rightarrow x^(2)+7 x-3 x-7 * 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 )