Describing the Behaviour of Functions f(x) is… increasing at … if f’(x) > 0 decreasing at … if f’(x) < 0 stationary at … if f’(x) = 0 Example {}𝑓(𝑥)=𝑥3+4𝑥2−3 𝑓(𝑥)=𝑥3+4𝑥2−3𝑓′(𝑥)=3𝑥2+8𝑥(𝑓′(𝑥)=0)3𝑥2+8𝑥=0𝑥(3𝑥+8)=0∴𝑥=0or−83 𝑓′(𝑥)>0∴𝑥<−83or𝑥>0 𝑓′(𝑥)<0∴−83<𝑥<0