Answer:
(x-5)(x+8)
x = 5
x = -8
Step-by-step explanation:
x^2+3x-40
Factorise
Two numbers that when added together gives +3 and when multiplied together gives -40.
The two numbers are +8 and -5
+8-5=+3
+8 X-5=-40
Hence, we substitute this two numbers with +3 in the equation above
x^2+8x-5x-40
We group into bracket
(x²+8x)-(5x+40)
In the first bracket, x is common while 5 is common in the second bracket
x(x+8)-5(x+8)
(x-5)(x+8)
x-5=0 x=5
x+8=0 x=-8
