Question

Help please, not sure how to do this....

Answer 1

Answer:

$4\sqrt{2b}$

Step-by-step explanation:

$\sqrt{98b}-\sqrt{72b}+\sqrt{18b}$

Apply radical rule $\sqrt{ab} =\sqrt{a} \sqrt{b}$:

$\implies \sqrt{98}\sqrt{b} -\sqrt{72}\sqrt{b} +\sqrt{18}\sqrt{b}$

Factor out common term $\sqrt{b}$:

$\implies \sqrt{b}(\sqrt{98} -\sqrt{72}+\sqrt{18})$

Rewrite 98, 72 and 18:

$\implies \sqrt{b}(\sqrt{49 \cdot 2} -\sqrt{36 \cdot 2}+\sqrt{9 \cdot 2})$

$\implies \sqrt{b}(\sqrt{49}\sqrt{2} -\sqrt{36}\sqrt{2}+\sqrt{9}\sqrt{2})$

$\implies \sqrt{b}(7\sqrt{2} -6\sqrt{2}+3\sqrt{2})$

Factor out common term $\sqrt{2}$:

$\implies \sqrt{b}\sqrt{2}(7 -6+3)$

$\implies \sqrt{b}\sqrt{2}(4)$

$\implies 4\sqrt{2b}$