Question

12x² - 7x + 1. Here the answer is (3x-1) (4x+1). Where did 4x comes from

Answer 1

Hey mate!!!!

Here's your answer!!

It's in the pic above.

Explaining you every step:
Well!
We need to find a pair of number which when multiplied by each other, results in 12×1 = 12.

So we'll first find out the factors of 12, which are:-
(i) 2 and 6
(ii) 3 and 4

Next, we're gonna find the pair ( from the above mentioned pairs) which when we added or subtracted from each other, results in (-7).

By adding (-3) and (-4), we get (-7).
That means, in place of (-7x) , we're gonna write (-3x) - 4x.

Next, we're gonna take them common and solve.
For more info:-

$\: REFER \: TO \: THE \: PIC!!$

Hope it helps!!!!

Cheers!!