Easy -1.2 This is a straightforward one-step equation requiring only basic manipulation of negative fractional indices. Students need to isolate x by raising both sides to the power of -2, then simplify to a fraction - purely procedural with no problem-solving required, making it easier than average.
\(4 = 7x^{\frac{1}{2}}\) or \(\frac{x^{\frac{1}{2}}}{4} = \frac{1}{7}\)
M1 (1.1a)
Order of M marks may vary. For getting their x term in numerator. \(\frac{4}{\frac{1}{x^2}} = 7\) not sufficient for this mark
Square both sides
M1 (1.1a)
e.g. \(\frac{x}{16} = \frac{1}{49}\)
\(x = \frac{16}{49}\)
A1 (1.1)
[3]
## Question 1:
| Answer/Working | Mark | Guidance |
|---|---|---|
| $4 = 7x^{\frac{1}{2}}$ or $\frac{x^{\frac{1}{2}}}{4} = \frac{1}{7}$ | M1 (1.1a) | Order of M marks may vary. For getting their x term in numerator. $\frac{4}{\frac{1}{x^2}} = 7$ not sufficient for this mark |
| Square both sides | M1 (1.1a) | e.g. $\frac{x}{16} = \frac{1}{49}$ |
| $x = \frac{16}{49}$ | A1 (1.1) | |
| **[3]** | | |
1 Solve the equation $4 x ^ { - \frac { 1 } { 2 } } = 7$, giving your answer as a fraction in its lowest terms.
\hfill \mbox{\textit{OCR MEI AS Paper 2 2019 Q1 [3]}}