Moderate -0.8 This is a straightforward substitution question requiring recognition that 4^(x+2) = 16ยท4^x, leading to a simple linear equation 16u - u = 16, so u = 16/15. The substitution is explicitly given, and solving for x requires only basic logarithms. Below average difficulty due to the guided approach and minimal problem-solving required.
Obtain \(u\) in any correct form, e.g. \(u = \frac{16}{16-1}\)
A1
Use correct method for solving an equation of the form \(4^x = a\), where \(a > 0\)
M1
Obtain answer \(x = 0.0466\)
A1
[4]
Use laws of indices correctly and solve for $u$ | M1 |
Obtain $u$ in any correct form, e.g. $u = \frac{16}{16-1}$ | A1 |
Use correct method for solving an equation of the form $4^x = a$, where $a > 0$ | M1 |
Obtain answer $x = 0.0466$ | A1 | [4]