Question

Find the factors of 2a2 + 9a − 18.

(2a − 3)(a + 6)

(2a + 3)(a − 6)

(2a − 9)(a + 2)

(2a − 2)(a + 9)

Answer 1

2a2 + 9a − 18.
I can give you the answer directly but do you want to know the ACTUAL method?

Answer 2

C

Answer 3

Not quite! :)
Do you want any explanation? :)

Answer 4

yes please

Answer 5

Let this be a quadratic eqqation!
ax2 + bx + c = 0
Now to find the roots we have to do something known as splitting the middle term like I had done in the previos video [Only difference in that case a was = 1 and here it is 2]
So to find out the middle terms we need 2 digits that multiply to
a*c AND add or subtract to 'b'
[Like in the last case they were 8 and 3 because when subtracted they gave b which was 5 and when multiplied they gave a*c = 24]

Answer 6

still dont get it

Answer 7

So in this case we need to find out numbers that multiply to 36 and add/subtract to give 9!
Two such numbers are? 12 and 3 [12-3 = 9 and 12*3 = 36]
Understood? :)
So write it like this!
2a2 + 9a − 18.
2a2 + 12a - 3a - 18
2a(a+6) - 3(a+6)
(2a-3)(a+6)
Got this? :)

Answer 8

yes thank you

Answer 9

:)