3m + 12 < 24
3m + 12 - 12 < 24 - 12
3m < 12
3/3m < 12/3
m < 4
Inc on (-inf,0)
Dec on (0,inf)
X² + x - 20 = 0
x² = x * x
x = the sum of the factors of -20
-20 ⇒ 1 x 20
2 x 10
- 4 x 5 ⇒ only these factors can arrive to a sum of 1
(x - 4)(x + 5) = x(x+5) - 4(x+5) = x² + 5x - 4x - 20 = x² + x - 20
x - 4 = 0
x = 4
x + 5 = 0
x = -5
25*3.14
78.5
hope this helps yw
