GCSE OCR Maths Indices: Martina has answered some questi

Question

Martina has answered some questions on algebra.
In each question, she has made an error.
Describe her error and give the correct answer to each problem.

(a) Question 1. Simplify: $2a 	imes a$
Martina's answer $4a$

Martina's error is that she miscalculated the product. The correct calculation is:
$$2a 	imes a = 2a^2$$

Correct answer = $2a^2$.

(b) Question 2. Simplify: $\frac{x^{10}}{x^2}$
Martina's answer $x^6$

Martina's error is that she incorrectly simplified the exponent. The correct simplification is:
$$\frac{x^{10}}{x^2} = x^{10-2} = x^8$$

Correct answer = $x^8$.

(c) Question 3. $s = ut + \frac{1}{2}at^2$
Find $s$ when $u = 0, t = 5$ and $a = 6$.
Martina's solution: $s = 0 	imes 5 + \frac{1}{2} 	imes 6 	imes 5^2$
$s = 0 + \frac{1}{2} 	imes 6 	imes 25$
$s = 0 + 75$
$s = 225$

Martina's error is in the evaluation of the expression where she did not simplify correctly before calculating. The correct calculation is:
$$s = ut + \frac{1}{2}at^2 = 0 + \frac{1}{2} 	imes 6 	imes (5^2)$$
$$ = 0 + \frac{1}{2} 	imes 6 	imes 25 = 75$$

Correct answer = $s = 75$.

Martina has answered some questions on algebra - OCR - GCSE Maths - Question 3 - 2019 - Paper 1

Worked Solution & Example Answer:Martina has answered some questions on algebra - OCR - GCSE Maths - Question 3 - 2019 - Paper 1

Question 1. Simplify: $2a \times a$

Question 2. Simplify: $\frac{x^{10}}{x^2}$

Question 3. $s = ut + \frac{1}{2}at^2$

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