Question

Factorise 
4y^2 12y -7

Answer 1

Note: The sign before the middle term is missing. So, I am doing two maths, one with plus and the other with minus. Follow the one which you require. 

('+' before middle term)

To factorise: $4y^2+12y-7$

=  $4y^2-2y+14y-7$

=  $2y(2y-1)+7(2y-1)$

=  $(2y-1)(2y+7)$

('-' before middle term)

To factorise: $4y^2-12y-7$

=  $4y^2+2y-14y-7$

=  $2y(2y+1)-7(2y+1)$

=  $(2y+1)(2y-7)$