This function is fraction so the easiest method is to use the quotient rule (though the product rule can be used). Recall the quotient rule dy/dx = [vu' - uv']/[v^2]Note, u and v refer to the numerator and denominator respectively u' and v' are the first differentials w.r.t x
For this question: u = 4x v = x^2 + 5 hence: u' = 4 v' = 2xApplying the quotient rule: [(x^2 + 5).(4) - (4x).(2x)]/[x^2 + 5]^2Expanding the brackets in the numerator: [4x^2 + 20 - 8x^2]/[x^2 + 5]^2Simplify: dy/dx = [20 -4x^2]/[x^2 + 5]^2No further cancellation or simplification can be done so, the question is finished.