JAMB Mathematics 2015 Paper

Concept:Use the product property of square roots to combine the radicals, then factor out perfect squares.Explanation:Start with the given product: $\sqrt{30} \times \sqrt{40}$.Using $\sqrt{a} \times \sqrt{b} = \sqrt{ab}$, combine the values inside one square root: $\sqrt{30 \times 40} = \sqrt{1200}$.To simplify, factor $1200$ into a perfect square and another factor: $1200 = 400 \times 3$.So $\sqrt{1200} = \sqrt{400 \times 3}$.Since $\sqrt{400} = 20$, split the radical: $\sqrt{400} \times \sqrt{3} = 20 \times \sqrt{3}$.Thus, the expression simplifies to $20\sqrt{3}$.Answer:$20\sqrt{3}$ Correct option: C.