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3 votes
Factorise a² + 3a - 40

2 Answers

7 votes

solution :

a²+3a-40

find the roots (2 numbers in which you can add and multiply to give 3a and 40)

(a-5) (a+8)

substitute the roots with 3a and multiply 40 by a²

a²-5a+8a-40a²

a(a-5) +8(a-40a²)

(a-5) (a+8)

User AndiGeeky
by
6.9k points
5 votes

Answer:

(a + 8)(a - 5)

Explanation:

a² + 3a - 40 =

= (a )( )

Find two numbers that multiply to -40 and add to 3.

They are 8 and -5.

= (a + 8)(a - 5)

User Ashleigh
by
7.5k points