Question

help, please see picture, and explain: no decimals please,​

Answer 1

$- \sqrt{72} = - \sqrt{2 {}^{3} \times 3 {}^{2} } = - 2 \times 3 \sqrt{2} = - 6 \sqrt{2}$

$- 4 \sqrt{8} = - 4 \sqrt{2 {}^{3} } = - 4 \times 2 \sqrt{2} = - 8 \sqrt{2}$

$- \sqrt{72} - 4 \sqrt{8} = - 6 \sqrt{2} - 8 \sqrt{2} = - 14 \sqrt{2}$