Evaluate: 2{28} - 3{50} + {72}

Correct Answer is : 47−92{7} - 9 {2}7−92

Correct Answer is : 47−92{7} - 9 {2}7−92

Test Index

WAEC Mathematics 2019 Paper

Question : 10

Total: 50

Evaluate: 2

\sqrt{28} - 3\sqrt{50} + \sqrt{72}

Solution:

Concept:

Simplify each square root first, then combine like terms.

Explanation:

Rewrite each radical in its simplest form.

2\sqrt{28} = 2 \times 2\sqrt{7} = 4\sqrt{7}

3\sqrt{50} = 3 \times 5\sqrt{2} = 15\sqrt{2}

\sqrt{72} = \sqrt{36 \times 2} = 6\sqrt{2}

Substitute these into the original expression.

4\sqrt{7} - 15\sqrt{2} + 6\sqrt{2}

Combine the

\sqrt{2}

terms:

-15\sqrt{2} + 6\sqrt{2} = -9\sqrt{2}

Keep the

\sqrt{7}

term unchanged:

4\sqrt{7}

Answer:

4\sqrt{7} - 9\sqrt{2}

Correct option: C.

4\sqrt{7} - 9\sqrt{2}

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