x2 + 3x - 40 = x2 + 8x - 5x - 40 = x(x + 8) - 5(x + 8) = (x - 5)(x + 8)
8(x+5) is equivalent to 8x+40
ANSWER: 88(1/2)(8 x 12) + 40:= (1/2 x 96) + 40= 88
(x - 5)(x - 8)
Factorise it: (x + 5)(3x - 8)
(x + 5)(x + 8)
x2 + 13x + 40 = x2 + 5x + 8x + 40 = x(x + 5) + 8(x + 5) = (x + 8)(x + 5)
8x + 8=40 8x=40-8 8x=32 x=32/8 x=4
x2 + 3x - 40 = x2 + 8x - 5x - 40 = x(x + 8) - 5(x + 8) = (x - 5)(x + 8)
8(x+5) is equivalent to 8x+40
x2 + 3x - 40 = (x + 8)(x - 5)
5(x=8)
3x + 2x = 40 5x = 40 x = 8
(x - 8)(x - 5)
ANSWER: 88(1/2)(8 x 12) + 40:= (1/2 x 96) + 40= 88
8(3 + 5) = (8 x 3) + (8 x 5) = 8 x 8 = 64
You should look for two numbers whose product is 40, and whose sum is 13. Experimenting a little (trying different pairs of factors for 40), you can quickly realize that this works for 8 and 5. Therefore, x2 + 13x + 40 = (x + 8) (x + 5)