Factorise f²-f-20 step by step

(f+4)(f−5)

Step-by-step explanation:

The middle number is -1 and the last number is -20.

Factoring means we want something like

(f+_)(f+_)

We need two numbers that...

Add together to get -1

Multiply together to get -20

4+-5 = -1

4*-5 = -20

Fill in the blanks in

(f+_)(f+_)

with 4 and -5 to get...

(f+4)(f-5)

Hey!!

Solution,

f^2-f-20

= f^2-(5-4)f-20

= f^2-5f+4f-20

= f(f-5)+4(f-5)

=(f-5)(f+4)

So the answer is (f-5)(f+4)

Hope it helps..

Good luck on your assignment