Hint
Multiply by the derivative of the complete inner function. Multiply by the inner derivative.
Worked solution
(a)
\(24 x + 60\) follows by differentiating each factor or inner function as required.
Answer: \(f'(x) = 24 x + 60\)
(b)
Differentiate the complete first derivative and simplify. \(24\)
Answer: \(24\)
(c)
The point has height \(75\) and gradient \(60\). Use \(y-y_0=m(x-x_0)\) to obtain \(y=60 x + 75\).
Answer: \(y=60 x + 75\)
Maths4U indicative marking guidance
Maths4U indicative marking guidance, not an official mark scheme. Credit complete valid alternatives and consequential reasoning; an unexplained final answer does not earn a method mark.
(a) · 2 marks
- 1 mark: Select and apply the differentiation rule, retaining every inner derivative.
- 1 mark: Obtain an algebraically equivalent complete derivative.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: An inner coefficient is not optional.
(b) · 2 marks
- 1 mark: Differentiate the first derivative consistently.
- 1 mark: Obtain the complete correct second derivative.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: Differentiate (bx+c) as b, not bx.
(c) · 2 marks
- 1 mark: Evaluate both the ordinate and derivative at the specified abscissa.
- 1 mark: Give a complete correct tangent equation.
Alternative methods: Any complete mathematically valid alternative method with the same restrictions and equivalent exact result is acceptable.
Common error: An inner coefficient is not optional.
Total: 6 marks.