WAEC Mathematics 2019 Objective — Question 10

Question 10 of 145 from the West African Examinations Council (WAEC) Mathematics 2019 Objective paper, with the correct answer and a full explanation.

10. Evaluate: 2√28 − 3√50 + √72.

A. 4√7 - 21√2
B. 4√7 - 11√2
C. 4√7 - 9√2Correct
D. 4√7 + √2

Explanation

Expressing in basic (simplest surd) form: 2√28=2×2√7=4√7; 3√50=3×5√2=15√2; √72=6√2. So 4√7−15√2+6√2 = 4√7−9√2.

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