Question

factorise the following 1. x²-2x+15.... 2. y²-19y+90​

Answer 1

1. x²-2x+15

This can't be factored, I've tried multiple ways now, but it just can't be factored.

2. y²-19y+90​

Let's factor y^2−19y+90

y^2−19y+90

The middle number is -19 and the last number is 90.

Factoring means we want something like

(y+_)(y+_)

Which numbers go in the blanks?

We need two numbers that...

Add together to get -19

Multiply together to get 90

Can you think of the two numbers?

Try -9 and -10:

-9+-10 = -19

-9*-10 = 90

Fill in the blanks in

(y+_)(y+_)

with -9 and -10 to get...

(y-9)(y-10)

Answer:

(y−9) (y−10)