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Calculate. (a) $(6^2 + 5)^3$ (b) $\sqrt{\frac{8.4^2 - 1.9^2}{2.5 + 5.7}}$ Write your answer correct to 3 significant figures. - OCR - GCSE Maths - Question 1 - 2021 - Paper 1

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Question 1

Calculate.-(a)-$(6^2-+-5)^3$--(b)-$\sqrt{\frac{8.4^2---1.9^2}{2.5-+-5.7}}$--Write-your-answer-correct-to-3-significant-figures.-OCR-GCSE Maths-Question 1-2021-Paper 1.png

Calculate. (a) $(6^2 + 5)^3$ (b) $\sqrt{\frac{8.4^2 - 1.9^2}{2.5 + 5.7}}$ Write your answer correct to 3 significant figures.

Worked Solution & Example Answer:Calculate. (a) $(6^2 + 5)^3$ (b) $\sqrt{\frac{8.4^2 - 1.9^2}{2.5 + 5.7}}$ Write your answer correct to 3 significant figures. - OCR - GCSE Maths - Question 1 - 2021 - Paper 1

Step 1

(a) $(6^2 + 5)^3$

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Answer

To solve the expression, we first calculate inside the parentheses:

  1. Calculate 626^2: 62=366^2 = 36

  2. Add 5: 36+5=4136 + 5 = 41

  3. Now cube the result: 413=41×41×41=6892141^3 = 41 \times 41 \times 41 = 68921

Thus, the answer for part (a) is 68921.

Step 2

(b) $\sqrt{\frac{8.4^2 - 1.9^2}{2.5 + 5.7}}$

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Answer

To solve this expression, follow these steps:

  1. Calculate 8.428.4^2: 8.42=70.568.4^2 = 70.56

  2. Calculate 1.921.9^2: 1.92=3.611.9^2 = 3.61

  3. Subtract the squares: 70.563.61=66.9570.56 - 3.61 = 66.95

  4. Add the denominator values: 2.5+5.7=8.22.5 + 5.7 = 8.2

  5. Calculate the fraction: 66.958.28.16\frac{66.95}{8.2} \approx 8.16

  6. Take the square root: 8.162.8579\sqrt{8.16} \approx 2.8579

Finally, round the answer to 3 significant figures: 2.862.86

Thus, the answer for part (b) is 2.86.

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