how to factorise by grouping for 7a, d and h

Step-by-step explanation:
7a
x2 + 4x + ax + 4a
x2 + ax + 4x + 4a
x (x + a) + 4 (x + a)
:(x + 4)(x+a)
7d
x2+2x-ax-2a
x2-ax+2x-2a
x (x-a)+2 (x-a)
:(x+2)(x-a)
7h
x2-2bx-5x+10b
x2-5x-2bx+10b
x (x-5)-2b(x-5)
:(x-2b)(x-5)
Answer:
You have to take out the common terms :
Question A,
[tex] {x}^{2} + 4x + ax + 4a[/tex]
[tex] = x(x + 4) + a(x + 4)[/tex]
[tex] = (x + a)(x + 4)[/tex]
Question D,
[tex] {x}^{2} + 2x - ax - 2a[/tex]
[tex] = x(x + 2) - a(x + 2)[/tex]
[tex] = (x - a)(x + 2)[/tex]
Question H,
[tex] {x}^{2} - 2bx - 5x + 10b[/tex]
[tex] = x(x - 2b) - 5(x - 2b)[/tex]
[tex] = (x - 5)(x - 2b)[/tex]