Đề: tính (có 2 câu ạ): a) $\sqrt{25}$ $-$ $\sqrt{81}$ $+$ $3$ $\sqrt{64}$ b) $3$$\sqrt{2}$ $-$ $5$$\sqrt{2}$ $+$ $\sqrt{8}$
2 câu trả lời
a) = `\sqrt{25}-\sqrt{81}+3\sqrt{64}`
= `\sqrt{5^2}-\sqrt{9^2}+3\sqrt{8^2}`
= `5-9+3.8`
= ` 5 - 9 + 24`
= `20`
b) `3\sqrt{2} - 5\sqrt{2} + \sqrt{8}`
= `3\sqrt{2} - 5\sqrt{2} + \sqrt{2^2 .2}`
= `3\sqrt{2} - 5\sqrt{2} + 2\sqrt{2}`
= `0`
$a)$ $\sqrt{25}-\sqrt{81}+3\sqrt{64}$
$=5-9+24$
$=20$
$b)$ $3\sqrt{2}-5\sqrt{2}+\sqrt{8}$
$=-2\sqrt{2}+\sqrt{8}$
$=-2\sqrt{2}+2\sqrt{2}$
$=0$