\(365289-56843+\sqrt{225}-\sqrt{81}=?\)
help me
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=>\(25\cdot\dfrac{\sqrt{a-3}}{5}-7\cdot\dfrac{2}{3}\cdot\sqrt{a-3}-7\sqrt{a^2-9}+18\cdot\dfrac{1}{3}\sqrt{a^2-9}=0\)
=>\(\sqrt{a-3}\cdot\dfrac{1}{3}-\sqrt{a^2-9}=0\)
=>\(\sqrt{a-3}\left(\dfrac{1}{3}-\sqrt{a+3}\right)=0\)
=>a-3=0 hoặc a+3=1/9
=>a=3 hoặc a=-26/9
Bài 1:
a) Ta có: \(\left(0.125\right)\cdot\left(-3\cdot7\right)\cdot\left(-2\right)^3\)
\(=\frac{1}{8}\cdot\left(-21\right)\cdot\left(-8\right)\)
\(=\frac{1}{8}\cdot168\)
\(=21\)
b) Ta có: \(\sqrt{36}\cdot\sqrt{\frac{25}{16}}+\frac{1}{4}\)
\(=\sqrt{36\cdot\frac{25}{16}}+\frac{1}{4}\)
\(=\sqrt{\frac{225}{4}}+\frac{1}{4}\)
\(=\frac{15}{2}+\frac{1}{4}\)
\(=\frac{31}{4}\)
c) Ta có: \(\sqrt{\frac{4}{81}}:\sqrt{\frac{25}{81}}-1\frac{2}{5}\)
\(=\frac{2}{9}:\frac{5}{9}-\frac{7}{5}\)
\(=\frac{2}{5}-\frac{7}{5}=-1\)
d) Ta có: \(0,1\cdot\sqrt{225}\cdot\sqrt{\frac{1}{4}}\)
\(=0,1\cdot15\cdot\frac{1}{2}=\frac{3}{4}\)
a) \(\sqrt{0,09}-\sqrt{0,64}=\frac{-1}{2}=-0,5\)
b) \(0,1\cdot\sqrt{225}-\sqrt{\frac{1}{4}}=0,1\cdot15-\frac{1}{2}=1\)
c) \(\sqrt{0,36}\cdot\sqrt{\frac{25}{16}+\frac{1}{4}}=\frac{3\sqrt{29}}{20}\)
d) đề baì có sai ko ban?
\(a.\sqrt{\dfrac{121}{225}}+\sqrt{\dfrac{16a^2}{81}}=\dfrac{11}{15}+\dfrac{-4a}{9}=\dfrac{33-20a}{45}\)
\(b.\sqrt{\dfrac{400}{49}}=\dfrac{20}{7}\)
\(c.\sqrt{\dfrac{\left(84-37\right)\left(84+37\right)}{47}}=\sqrt{121}=11\)
a: \(=2\sqrt{20\sqrt{3}}-2\sqrt{5\sqrt{3}}-3\cdot\sqrt{20\sqrt{3}}\)
\(=4\sqrt{5\sqrt{3}}-2\sqrt{5\sqrt{3}}-6\sqrt{5\sqrt{3}}=-4\sqrt{5\sqrt{3}}\)
b: \(=2\sqrt{5\sqrt{3}}-4\sqrt{2\sqrt{3}}-6\sqrt{5\sqrt{3}}=-4\sqrt{5\sqrt{3}}-4\sqrt{2\sqrt{3}}\)
\(\sqrt{\left(\sqrt{3}-2\right)^2}+\sqrt{\left(3-\sqrt{3}\right)^2}\)
\(=\left|\sqrt{3}-2\right|+\left|3-\sqrt{3}\right|\)
\(=2-\sqrt{3}+3-\sqrt{3}\)
\(=5-2\sqrt{3}\)
\(\sqrt{25t^2-9}=2\sqrt{5t-3}\left(t\ge\dfrac{3}{5}\right)\)hoặc\(t\le-\dfrac{3}{5}\))
\(=\sqrt{\left(5t-3\right)\left(5t+3\right)}-2\sqrt{5t-3}=0\)
\(< =>\sqrt{5t-3}\left(\sqrt{5t+3}-2\right)=0\)
\(=>\left[{}\begin{matrix}\sqrt{5t-3}=0\\\sqrt{5t+3}-2=0\end{matrix}\right.< =>\left[{}\begin{matrix}t=0,6\left(TM\right)\\t=0,2\left(loai\right)\end{matrix}\right.\)
vậy t=0,6
\(\sqrt{-2x^2+6}=x-1\)(\(-\sqrt{3}\le x\le\sqrt{3}\) \(\))
\(=>-2x^2+6=x^2-2x+1\)
\(< =>-3x^2+2x+5=0\)
\(\Delta=\left(2\right)^2-4.5.\left(-3\right)=64>0\)
\(=>\left[{}\begin{matrix}x1=\dfrac{-2+\sqrt{64}}{2\left(-3\right)}=-1\left(loai\right)\\x2=\dfrac{-2-\sqrt{64}}{2\left(-3\right)}=\dfrac{5}{3}\left(TM\right)\end{matrix}\right.\)vậy x=5/3
365289-56843+\(\sqrt{225}\)-\(\sqrt{81}\)=308452.
có cả căn bậc 2 sao lại để là toán lớp 1 vậy bn?