http://prntscr.com/8gj6a8

I need a full step explanation.

Question

http://prntscr.com/8gj6a8



I need a full step explanation.

marigirl · Answer

|dw:1442308220092:dw|

So basically what they are asking is that .. what can you multiple (x+15) by in order to obtain $$x^2+18x+45$$

marigirl · Answer

Here our factorising skills can come in handy. Can you factorize (i.e split into a pair of brackets) $$x^2+18x+45$$
We know from the question one set of these brackets is going to be (x+15)

marigirl · Answer

Can you see what im getting at?

$$(x+15)(x+?)=x^2+18x+45$$

marigirl · Answer

I need two numbers that will multiply to 45 and those two very same numbers must add to 18.... I already have a clue to use 15 .. so what will be the other number?

jhannybean · Answer

$$\text{hi}$$

anonymous · Answer

factorise it

anonymous · Answer

$$x ^{2} + 18x +45 $$

anonymous · Answer

do u know how to factorise ?

anonymous · Answer

so basically you must get two values when add gives you +18 and when multiply you get +45