Easy -1.2 This is a straightforward application of the chain rule to differentiate ln(5x+1), giving dy/dx = 5/(5x+1), followed by direct substitution of x=4. It requires only one standard technique with no problem-solving or conceptual challenge, making it easier than average.
Obtain derivative of the form \(\frac{k}{5x+1}\), where \(k = 1, 5\) or \(\frac{1}{5}\)
M1
Obtain correct derivative \(\frac{5}{5x+1}\)
A1
Substitute \(x = 4\) into expression for derivative and obtain \(\frac{5}{21}\)
A1√
[3]
Obtain derivative of the form $\frac{k}{5x+1}$, where $k = 1, 5$ or $\frac{1}{5}$ | M1 |
Obtain correct derivative $\frac{5}{5x+1}$ | A1 |
Substitute $x = 4$ into expression for derivative and obtain $\frac{5}{21}$ | A1√ | [3]