Solve each of these inequalities. Sketch the curve for each, showing the interval that satisfies each inequality.

a) x² + 7x + 12 ≤ 0

b) x² –  x – 30 < 0

c) x² + 2x – 48 > 0  

d) x³ – 5x + 6 ≥ 0

e) 2x² – 11x + 12 > 0

f)   3x² + 14x – 5 ≤ 0

g) 15 + 2x – x² ≤ 0

h) 16 – 6x – x² < 0

i) 21– x – 2x² > 0

j) 10x² + 43x + 28 ≥ 0

k) x² –  9 ≥ 0

l) 50 – 2x³ < 0