Toán Lớp 9: Đề: tính (có 2 câu ạ):
a) $\sqrt{25}$ $-$ $\sqrt{81}$ $+$ $3$ $\sqrt{64}$
b) $3$$\sqrt{2}$ $-$ $5$$\sqrt{2}$ $+$ $\sqrt{8}$
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Toán Lớp 9: Đề: tính (có 2 câu ạ):
a) $\sqrt{25}$ $-$ $\sqrt{81}$ $+$ $3$ $\sqrt{64}$
b) $3$$\sqrt{2}$ $-$ $5$$\sqrt{2}$ $+$ $\sqrt{8}$
Comments ( 2 )
$a)$ $\sqrt{25}-\sqrt{81}+3\sqrt{64}$
$=5-9+24$
$=20$
$b)$ $3\sqrt{2}-5\sqrt{2}+\sqrt{8}$
$=-2\sqrt{2}+\sqrt{8}$
$=-2\sqrt{2}+2\sqrt{2}$
$=0$
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