Factorize the right side of the equations

a

r  =  a² + 12a       Factor an  a  out of both terms on the right side.

r  =  a(a + 12)

 

b

s  =  b² - 8b + 7

s  =  b² - 8b + 7       What two numbers that add to  -8  and multiply to  7 ?    -7  and  -1

                                So the right side factors like this...

s  =  (b - 7)(b - 1)

 

c

t  =  c² - c - 30

t  =  c² - 1c - 30          What two numbers add to  -1  and multiply to  -30 ?   +5  and  -6  . So....

t  =  (c + 5)(c - 6)

 

d

u  =  d² + 6d - 7

u  =  d² + 6d - 7        What two numbers add to  6  and multiply to  -7 ?   +7  and  -1  . So...

u  =  (d + 7)(d - 1)