How do you factor the trinomial $9r^2+15r+6$ ?

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Answer 1 · 2016-02-23T17:32:36

$= (9 r +6) ( r +1)$

$9r^2 +15r +6$

We can Split the Middle Term of this expression to factorise it.

In this technique, if we have to factorise an expression like $ar^2 + br + c$ , we need to think of 2 numbers such that:

$N_1*N_2 = a*c = 9*6 =54$
AND
$N_1 +N_2 = b = 15$

After trying out a few numbers we get $N_1 = 6$ and $N_2 =9$
$9*6 = 54$ , and $9 +6=15$

$9r^2 +15r +6 =9r^2 +9r +6r +6$

$= 9 r ( r +1) +6 (r +1 )$

$= (9 r +6) ( r +1)$

How do you factor the trinomial 9r^2+15r+69r^2+15r+6?