An automated solar tracker follows a path defined by the function
H(ϕ)=ϕ4+12ϕ2+24cosϕ H(\phi) = \phi^4 + 12\phi^2 + 24\cos \phi H(ϕ)=ϕ4+12ϕ2+24cosϕfor −π≤ϕ≤π-\pi \le \phi \le \pi−π≤ϕ≤π, where HHH is the vertical displacement in decimeters and ϕ\phiϕ is the angle of rotation in radians. Determine whether the curve with equation y=H(ϕ)y = H(\phi)y=H(ϕ) has a point of inflection at the point where ϕ=0\phi = 0ϕ=0. Fully justify your answer.
333 exam-style questions on WJEC A Level Maths 3.6 Differentiation (A-level only), covering 3.6.1 Differentiation (A-level only), 3.6.2 Differentiation (A-level only), 3.6.3 Differentiation (A-level only), 3.6.4 Differentiation (A-level only), 3.6.5 Differentiation (A-level only), 3.6.6 Differentiation (A-level only), 3.6.7 Differentiation (A-level only), and 3.6 Differentiation (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.