x²+3x-40
(x+8)(x-5)
To factorise the quadratic expression x² + 3x – 40, you need to find two numbers that multiply to give -40 and add up to 3.
Here’s one way to approach the problem:
1. Make a list of all the factor pairs of -40:
-1 and 40
-2 and 20
-4 and 10
-5 and 8
2. Find which pair of factors adds up to 3.
The pair -5 and 8 adds up to 3.
3. Rewrite the quadratic expression using the pair of factors that add up to 3.
x² – 5x + 8x – 40
4. Factorise by grouping.
(x² – 5x) + (8x – 40)
x(x – 5) + 8(x – 5)
(x – 5)(x + 8)
Therefore, the factorised form of the quadratic expression x² + 3x – 40 is (x – 5)(x + 8).
More Answers:
[next_post_link]