1. 计算:
(1)$\sqrt{27}-\sqrt{\dfrac{3}{2}}× \sqrt{8}$; (2)$\sqrt{12}+3\sqrt{1\dfrac{1}{3}}-\sqrt{27}$;
(3)$(\sqrt{24}-2\sqrt{\dfrac{3}{2}}+3\sqrt{2\dfrac{2}{3}})× \sqrt{3}$; (4)$(3\sqrt{18}+\dfrac{1}{5}\sqrt{50}-4\sqrt{\dfrac{1}{2}})÷ \sqrt{32}$;
(5)$\sqrt{12}× \sqrt{\dfrac{3}{2}}-\sqrt{10}÷ \sqrt{5}+\sqrt{8}$; (6)$\sqrt{\dfrac{2}{25}}-\sqrt{6}+2\sqrt{2}× \dfrac{\sqrt{2}}{4}÷ 5\sqrt{2}$.
(1)$\sqrt{27}-\sqrt{\dfrac{3}{2}}× \sqrt{8}$; (2)$\sqrt{12}+3\sqrt{1\dfrac{1}{3}}-\sqrt{27}$;
(3)$(\sqrt{24}-2\sqrt{\dfrac{3}{2}}+3\sqrt{2\dfrac{2}{3}})× \sqrt{3}$; (4)$(3\sqrt{18}+\dfrac{1}{5}\sqrt{50}-4\sqrt{\dfrac{1}{2}})÷ \sqrt{32}$;
(5)$\sqrt{12}× \sqrt{\dfrac{3}{2}}-\sqrt{10}÷ \sqrt{5}+\sqrt{8}$; (6)$\sqrt{\dfrac{2}{25}}-\sqrt{6}+2\sqrt{2}× \dfrac{\sqrt{2}}{4}÷ 5\sqrt{2}$.
答案:1. (1)
解:
先化简各项:
$\sqrt{27}=\sqrt{9×3}=3\sqrt{3}$,$\sqrt{\frac{3}{2}}×\sqrt{8}=\sqrt{\frac{3}{2}×8}=\sqrt{12}=2\sqrt{3}$。
再计算:
$\sqrt{27}-\sqrt{\frac{3}{2}}×\sqrt{8}=3\sqrt{3}-2\sqrt{3}=\sqrt{3}$。
2. (2)
解:
先化简各项:
$\sqrt{12}=\sqrt{4×3}=2\sqrt{3}$,$3\sqrt{1\frac{1}{3}}=3\sqrt{\frac{4}{3}}=3×\frac{2}{\sqrt{3}} = 2\sqrt{3}$,$\sqrt{27}=\sqrt{9×3}=3\sqrt{3}$。
再计算:
$\sqrt{12}+3\sqrt{1\frac{1}{3}}-\sqrt{27}=2\sqrt{3}+2\sqrt{3}-3\sqrt{3}=\sqrt{3}$。
3. (3)
解:
先化简各项:
$\sqrt{24}=\sqrt{4×6}=2\sqrt{6}$,$2\sqrt{\frac{3}{2}}=\sqrt{4×\frac{3}{2}}=\sqrt{6}$,$3\sqrt{2\frac{2}{3}}=3\sqrt{\frac{8}{3}}=3×\frac{2\sqrt{6}}{3}=2\sqrt{6}$。
再计算:
$(\sqrt{24}-2\sqrt{\frac{3}{2}}+3\sqrt{2\frac{2}{3}})×\sqrt{3}=(2\sqrt{6}-\sqrt{6}+2\sqrt{6})×\sqrt{3}=3\sqrt{6}×\sqrt{3}=9\sqrt{2}$。
4. (4)
解:
先化简各项:
$3\sqrt{18}=3\sqrt{9×2}=9\sqrt{2}$,$\frac{1}{5}\sqrt{50}=\frac{1}{5}\sqrt{25×2}=\sqrt{2}$,$4\sqrt{\frac{1}{2}}=2\sqrt{2}$,$\sqrt{32}=\sqrt{16×2}=4\sqrt{2}$。
再计算:
$(3\sqrt{18}+\frac{1}{5}\sqrt{50}-4\sqrt{\frac{1}{2}})÷\sqrt{32}=(9\sqrt{2}+\sqrt{2}-2\sqrt{2})÷4\sqrt{2}=8\sqrt{2}÷4\sqrt{2}=2$。
5. (5)
解:
先化简各项:
$\sqrt{12}×\sqrt{\frac{3}{2}}=\sqrt{12×\frac{3}{2}}=\sqrt{18}=3\sqrt{2}$,$\sqrt{10}÷\sqrt{5}=\sqrt{2}$,$\sqrt{8}=2\sqrt{2}$。
再计算:
$\sqrt{12}×\sqrt{\frac{3}{2}}-\sqrt{10}÷\sqrt{5}+\sqrt{8}=3\sqrt{2}-\sqrt{2}+2\sqrt{2}=4\sqrt{2}$。
6. (6)
解:
先化简各项:
$\sqrt{\frac{2}{25}}=\frac{\sqrt{2}}{5}$,$2\sqrt{2}×\frac{\sqrt{2}}{4}÷5\sqrt{2}=\frac{2×2}{4}÷5\sqrt{2}=\frac{1}{5\sqrt{2}}=\frac{\sqrt{2}}{10}$。
再计算:
$\sqrt{\frac{2}{25}}-\sqrt{6}+2\sqrt{2}×\frac{\sqrt{2}}{4}÷5\sqrt{2}=\frac{\sqrt{2}}{5}-\sqrt{6}+\frac{\sqrt{2}}{10}=\frac{3\sqrt{2}}{10}-\sqrt{6}$。
综上,答案依次为:(1)$\sqrt{3}$;(2)$\sqrt{3}$;(3)$9\sqrt{2}$;(4)$2$;(5)$4\sqrt{2}$;(6)$\frac{3\sqrt{2}}{10}-\sqrt{6}$。
解:
先化简各项:
$\sqrt{27}=\sqrt{9×3}=3\sqrt{3}$,$\sqrt{\frac{3}{2}}×\sqrt{8}=\sqrt{\frac{3}{2}×8}=\sqrt{12}=2\sqrt{3}$。
再计算:
$\sqrt{27}-\sqrt{\frac{3}{2}}×\sqrt{8}=3\sqrt{3}-2\sqrt{3}=\sqrt{3}$。
2. (2)
解:
先化简各项:
$\sqrt{12}=\sqrt{4×3}=2\sqrt{3}$,$3\sqrt{1\frac{1}{3}}=3\sqrt{\frac{4}{3}}=3×\frac{2}{\sqrt{3}} = 2\sqrt{3}$,$\sqrt{27}=\sqrt{9×3}=3\sqrt{3}$。
再计算:
$\sqrt{12}+3\sqrt{1\frac{1}{3}}-\sqrt{27}=2\sqrt{3}+2\sqrt{3}-3\sqrt{3}=\sqrt{3}$。
3. (3)
解:
先化简各项:
$\sqrt{24}=\sqrt{4×6}=2\sqrt{6}$,$2\sqrt{\frac{3}{2}}=\sqrt{4×\frac{3}{2}}=\sqrt{6}$,$3\sqrt{2\frac{2}{3}}=3\sqrt{\frac{8}{3}}=3×\frac{2\sqrt{6}}{3}=2\sqrt{6}$。
再计算:
$(\sqrt{24}-2\sqrt{\frac{3}{2}}+3\sqrt{2\frac{2}{3}})×\sqrt{3}=(2\sqrt{6}-\sqrt{6}+2\sqrt{6})×\sqrt{3}=3\sqrt{6}×\sqrt{3}=9\sqrt{2}$。
4. (4)
解:
先化简各项:
$3\sqrt{18}=3\sqrt{9×2}=9\sqrt{2}$,$\frac{1}{5}\sqrt{50}=\frac{1}{5}\sqrt{25×2}=\sqrt{2}$,$4\sqrt{\frac{1}{2}}=2\sqrt{2}$,$\sqrt{32}=\sqrt{16×2}=4\sqrt{2}$。
再计算:
$(3\sqrt{18}+\frac{1}{5}\sqrt{50}-4\sqrt{\frac{1}{2}})÷\sqrt{32}=(9\sqrt{2}+\sqrt{2}-2\sqrt{2})÷4\sqrt{2}=8\sqrt{2}÷4\sqrt{2}=2$。
5. (5)
解:
先化简各项:
$\sqrt{12}×\sqrt{\frac{3}{2}}=\sqrt{12×\frac{3}{2}}=\sqrt{18}=3\sqrt{2}$,$\sqrt{10}÷\sqrt{5}=\sqrt{2}$,$\sqrt{8}=2\sqrt{2}$。
再计算:
$\sqrt{12}×\sqrt{\frac{3}{2}}-\sqrt{10}÷\sqrt{5}+\sqrt{8}=3\sqrt{2}-\sqrt{2}+2\sqrt{2}=4\sqrt{2}$。
6. (6)
解:
先化简各项:
$\sqrt{\frac{2}{25}}=\frac{\sqrt{2}}{5}$,$2\sqrt{2}×\frac{\sqrt{2}}{4}÷5\sqrt{2}=\frac{2×2}{4}÷5\sqrt{2}=\frac{1}{5\sqrt{2}}=\frac{\sqrt{2}}{10}$。
再计算:
$\sqrt{\frac{2}{25}}-\sqrt{6}+2\sqrt{2}×\frac{\sqrt{2}}{4}÷5\sqrt{2}=\frac{\sqrt{2}}{5}-\sqrt{6}+\frac{\sqrt{2}}{10}=\frac{3\sqrt{2}}{10}-\sqrt{6}$。
综上,答案依次为:(1)$\sqrt{3}$;(2)$\sqrt{3}$;(3)$9\sqrt{2}$;(4)$2$;(5)$4\sqrt{2}$;(6)$\frac{3\sqrt{2}}{10}-\sqrt{6}$。
2. 计算:
(1)$(2+\sqrt{3})(2-\sqrt{3})+(\sqrt{2}-\sqrt{3})^{2}$; (2)$\dfrac{3-\sqrt{12}}{\sqrt{3}}+(3+\sqrt{3})(3-\sqrt{3})$;
(3)$\vert -\sqrt{2}\vert +(\sqrt{2}-\dfrac{1}{2})^{2}-(\sqrt{2}+\dfrac{1}{2})^{2}$; (4)$(2\sqrt{5}+3\sqrt{2})^{2}-(2\sqrt{5}-3\sqrt{2})^{2}$;
(5)$(4+\sqrt{15})^{2025}× (4-\sqrt{15})^{2026}$; (6)$(1+\sqrt{2}+\sqrt{3})× (1+\sqrt{2}-\sqrt{3})$.
(1)$(2+\sqrt{3})(2-\sqrt{3})+(\sqrt{2}-\sqrt{3})^{2}$; (2)$\dfrac{3-\sqrt{12}}{\sqrt{3}}+(3+\sqrt{3})(3-\sqrt{3})$;
(3)$\vert -\sqrt{2}\vert +(\sqrt{2}-\dfrac{1}{2})^{2}-(\sqrt{2}+\dfrac{1}{2})^{2}$; (4)$(2\sqrt{5}+3\sqrt{2})^{2}-(2\sqrt{5}-3\sqrt{2})^{2}$;
(5)$(4+\sqrt{15})^{2025}× (4-\sqrt{15})^{2026}$; (6)$(1+\sqrt{2}+\sqrt{3})× (1+\sqrt{2}-\sqrt{3})$.
答案:2.(1)
$\begin{aligned}&(2 + \sqrt{3})(2 - \sqrt{3}) + (\sqrt{2} - \sqrt{3})^2\\=&2^2 - (\sqrt{3})^2 + (\sqrt{2})^2 - 2\sqrt{2}×\sqrt{3} + (\sqrt{3})^2\\=&4 - 3 + 2 - 2\sqrt{6} + 3\\=&6 - 2\sqrt{6}\end{aligned}$
(2)
$\begin{aligned}&\frac{3 - \sqrt{12}}{\sqrt{3}} + (3 + \sqrt{3})(3 - \sqrt{3})\\=&\frac{3 - 2\sqrt{3}}{\sqrt{3}} + 3^2 - (\sqrt{3})^2\\=&\sqrt{3} - 2 + 9 - 3\\=&\sqrt{3} + 4\end{aligned}$
(3)
$\begin{aligned}&|-\sqrt{2}| + (\sqrt{2} - \frac{1}{2})^2 - (\sqrt{2} + \frac{1}{2})^2\\=&\sqrt{2} + [(\sqrt{2} - \frac{1}{2}) + (\sqrt{2} + \frac{1}{2})][(\sqrt{2} - \frac{1}{2}) - (\sqrt{2} + \frac{1}{2})]\\=&\sqrt{2} + (2\sqrt{2})×(-1)\\=&\sqrt{2} - 2\sqrt{2}\\=&-\sqrt{2}\end{aligned}$
(4)
$\begin{aligned}&(2\sqrt{5} + 3\sqrt{2})^2 - (2\sqrt{5} - 3\sqrt{2})^2\\=&[(2\sqrt{5} + 3\sqrt{2}) + (2\sqrt{5} - 3\sqrt{2})][(2\sqrt{5} + 3\sqrt{2}) - (2\sqrt{5} - 3\sqrt{2})]\\=&(4\sqrt{5})×(6\sqrt{2})\\=&24\sqrt{10}\end{aligned}$
(5)
$\begin{aligned}&(4 + \sqrt{15})^{2025}× (4 - \sqrt{15})^{2026}\\=&(4 + \sqrt{15})^{2025}× (4 - \sqrt{15})^{2025}× (4 - \sqrt{15})\\=&[(4 + \sqrt{15})(4 - \sqrt{15})]^{2025}× (4 - \sqrt{15})\\=&(16 - 15)^{2025}× (4 - \sqrt{15})\\=&1× (4 - \sqrt{15})\\=&4 - \sqrt{15}\end{aligned}$
(6)
$\begin{aligned}&(1 + \sqrt{2} + \sqrt{3})× (1 + \sqrt{2} - \sqrt{3})\\=&[(1 + \sqrt{2}) + \sqrt{3}][(1 + \sqrt{2}) - \sqrt{3}]\\=&(1 + \sqrt{2})^2 - (\sqrt{3})^2\\=&1 + 2\sqrt{2} + 2 - 3\\=&2\sqrt{2}\end{aligned}$
$\begin{aligned}&(2 + \sqrt{3})(2 - \sqrt{3}) + (\sqrt{2} - \sqrt{3})^2\\=&2^2 - (\sqrt{3})^2 + (\sqrt{2})^2 - 2\sqrt{2}×\sqrt{3} + (\sqrt{3})^2\\=&4 - 3 + 2 - 2\sqrt{6} + 3\\=&6 - 2\sqrt{6}\end{aligned}$
(2)
$\begin{aligned}&\frac{3 - \sqrt{12}}{\sqrt{3}} + (3 + \sqrt{3})(3 - \sqrt{3})\\=&\frac{3 - 2\sqrt{3}}{\sqrt{3}} + 3^2 - (\sqrt{3})^2\\=&\sqrt{3} - 2 + 9 - 3\\=&\sqrt{3} + 4\end{aligned}$
(3)
$\begin{aligned}&|-\sqrt{2}| + (\sqrt{2} - \frac{1}{2})^2 - (\sqrt{2} + \frac{1}{2})^2\\=&\sqrt{2} + [(\sqrt{2} - \frac{1}{2}) + (\sqrt{2} + \frac{1}{2})][(\sqrt{2} - \frac{1}{2}) - (\sqrt{2} + \frac{1}{2})]\\=&\sqrt{2} + (2\sqrt{2})×(-1)\\=&\sqrt{2} - 2\sqrt{2}\\=&-\sqrt{2}\end{aligned}$
(4)
$\begin{aligned}&(2\sqrt{5} + 3\sqrt{2})^2 - (2\sqrt{5} - 3\sqrt{2})^2\\=&[(2\sqrt{5} + 3\sqrt{2}) + (2\sqrt{5} - 3\sqrt{2})][(2\sqrt{5} + 3\sqrt{2}) - (2\sqrt{5} - 3\sqrt{2})]\\=&(4\sqrt{5})×(6\sqrt{2})\\=&24\sqrt{10}\end{aligned}$
(5)
$\begin{aligned}&(4 + \sqrt{15})^{2025}× (4 - \sqrt{15})^{2026}\\=&(4 + \sqrt{15})^{2025}× (4 - \sqrt{15})^{2025}× (4 - \sqrt{15})\\=&[(4 + \sqrt{15})(4 - \sqrt{15})]^{2025}× (4 - \sqrt{15})\\=&(16 - 15)^{2025}× (4 - \sqrt{15})\\=&1× (4 - \sqrt{15})\\=&4 - \sqrt{15}\end{aligned}$
(6)
$\begin{aligned}&(1 + \sqrt{2} + \sqrt{3})× (1 + \sqrt{2} - \sqrt{3})\\=&[(1 + \sqrt{2}) + \sqrt{3}][(1 + \sqrt{2}) - \sqrt{3}]\\=&(1 + \sqrt{2})^2 - (\sqrt{3})^2\\=&1 + 2\sqrt{2} + 2 - 3\\=&2\sqrt{2}\end{aligned}$