Given that y = e³ˣ / (4x² + 1), find dy/dx.
- (a)Given that y = e³ˣ / (4x² + 1), find dy/dx.[3]
- (b)(i)Find the value of dy/dx when x = π/2.[3]
- (b)(ii)Find the value of dx/dt when x = π/2.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.
- [M1] differentiation of a quotient or equivalent product
- [B1] correct differentiation of e³ˣ
- [A1] dy/dx = (3e³ˣ(4x²+1)-8xe³ˣ)/(4x²+1)² or dy/dx = e³ˣ ( (3(4x²+1)-8x) / (4x²+1)² ) everything else correct including brackets where needed, allow unsimplified
- [M1] one term differentiated correctly
- [A1] dy/dx = -4sin(x+π/3) + 2√3cos(x+π/3) all correct
- [A1] When x = π/2, dy/dx = -5
- [M1] dy/dt = dy/dx * dx/dt correct use of rates of change
- [A1] dx/dt = -2 FT answer to (i)
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