Factoring Help (2 Problems)?

Question

Factor completely

1)
6x2 + 21x - 45


2)

a2 + ab + 2a + 2b

Answer 1

The answer to the first question is:
3(x + 5) (2x - 3)
and to the second is:
(a+2)(a+b).
A previous answer has treated the first question as an equation, and as a result left out the factor of 3.

Answer 2

1)To make the calculations easier, we can use the fact that the coefficients 6, 21 and -45 have a common factor of 3.

Dividing both sides by 3 then gives the simpler but equivalent equation :

2 x2 + 7 x - 15 = 0

After factoring the quadratic on the left hand side , we can rewrite

2 x2 + 7 x - 15 = 0

as

( x + 5 ) ( 2x - 3 ) = 0


2) (a+2)(a+b)

Answer 3

1)take out a 3 first...3(2x^2+7x-15)

2) group them first (a^2 +ab) (2a+2b)
then take out the a on first set you get a(a+b) then take out the 2 on the second set. you get 2(a+b)
then group the like
answer (a+2)(a+b)

Answer 4

Same as above.

( x + 5 ) ( 2x - 3 )

(a+2)(a+b)