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Bài 1:
a; (\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\)) x \(\dfrac{3}{4}\) = \(\dfrac{1}{4}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) : \(\dfrac{3}{4}\)
\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) x \(\dfrac{4}{3}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{3}\)
\(\dfrac{1}{4}x\) = \(\dfrac{1}{3}\) + \(\dfrac{1}{8}\)
\(\dfrac{1}{4}\) \(x\)= \(\dfrac{8}{24}\) + \(\dfrac{11}{24}\)
\(\dfrac{1}{4}x=\dfrac{11}{24}\)
\(x=\dfrac{11}{24}:\dfrac{1}{4}\)
\(x=\dfrac{11}{24}\times4\)
\(x=\dfrac{11}{6}\)
b; \(\dfrac{12}{5}:x\) = \(\dfrac{14}{3}\) x \(\dfrac{4}{7}\)
\(\dfrac{12}{5}\) : \(x\) = \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) : \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) x \(\dfrac{3}{8}\)
\(x\) = \(\dfrac{9}{10}\)
1.(2515.415)/(517.2016)=(530.230)/(517.516.232)=1/(53.22)=1/500
2.a,-x/2=8/-x=>-x.(-x)=2*8 =>x^2=16=(-4)^2=4^2
=>x=4 hoặc x=-4
b,(3/4)2x/(2/5)10=(15/8)10
(3/4)2x=(2/5*15/8)10
(3/4)2x=(3/4)10
2x=10
x=5
1) \(\frac{25^{15}\cdot4^{15}}{5^{17}\cdot20^{16}}\)
\(=\frac{5^{30}\cdot2^{30}}{5^{33}\cdot2^{32}}\)
\(=\frac{1}{5^3\cdot2^2}\)
\(=\frac{1}{500}\)
2)
a) \(\frac{-x}{2}=\frac{8}{-x}\)
\(\Rightarrow\left(-x\right)\left(-x\right)=8\cdot2\)
\(\Rightarrow x^2=16\)
\(\Rightarrow x=\left\{\pm4\right\}\)
\(A=\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{3}{8}+\frac{-6}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{-3}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{-36}{24}+\frac{56}{24}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\frac{5}{6}:\frac{5}{6}+\frac{1}{2}\)
\(A=\frac{5}{6}\times\frac{6}{5}+\frac{1}{2}\)
\(A=1+\frac{1}{2}\)
\(A=\frac{1}{1}+\frac{1}{2}=\frac{2}{2}+\frac{1}{2}\)
\(A=\frac{3}{2}\)
Đáp án: thiếu đề
@#@
mời bn xem xét lại đề bài.
~hok tốt~
Bài 1:
a)
\(\frac{8^{20}+4^{20}}{4^{25}+64^5}=\frac{(2^3)^{20}+(2^2)^{20}}{(2^2)^{25}+(2^6)^{5}}=\frac{2^{60}+2^{40}}{2^{50}+2^{30}}=\frac{2^{40}(2^{20}+1)}{2^{30}(2^{20}+1)}=2^{10}\)
b)
\(\frac{45^{10}.5^{20}}{75^{15}}=\frac{(3^2.5)^{10}.5^{20}}{(3.5^2)^{15}}=\frac{3^{20}5^{30}}{3^{15}.5^{30}}=\frac{3^{20}}{3^{15}}=3^5\)
Bài 2:
Ta thấy $(x-2)^{2012}=[(x-2)^{1006}]^2\geq 0$ với mọi $x\in\mathbb{R}$
$|b^2-9|^{2014|\geq 0$ với mọi $b\in\mathbb{R}$ (tính chất trị tuyệt đối)
Do đó để tổng của chúng bằng $0$ thì:
\((x-2)^{2012}=|b^2-9|^{2014}=0\)
\(\Leftrightarrow \left\{\begin{matrix} x-2=0\\ b^2-9=0\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} x=2\\ b=\pm 3\end{matrix}\right.\)
Vậy.......
Tính :
a) \(\frac{8^{14}}{4^{12}}=\frac{\left(2^3\right)^{14}}{\left(2^2\right)^{12}}=\frac{2^{42}}{2^{24}}=2^{18}=262144.\)
b) \(\frac{120^3}{40^3}=\left(\frac{120}{40}\right)^3=3^3=27.\)
Tìm x:
b) \(x^2-0,25=0\)
\(\Rightarrow x^2=0+0,25\)
\(\Rightarrow x^2=0,25\)
\(\Rightarrow\left[{}\begin{matrix}x=0,5\\x=-0,5\end{matrix}\right.\)
Vậy \(x\in\left\{0,5;-0,5\right\}.\)
c) \(\frac{8}{2^x}=2\)
\(\Rightarrow2^x=8:2\)
\(\Rightarrow2^x=4\)
\(\Rightarrow2^x=2^2\)
\(\Rightarrow x=2\)
Vậy \(x=2.\)
Chúc bạn học tốt!
a, 2 mũ 17 phần 2 mũ 14
b,=30
mình chỉ làm được 2 câu thôi,chúc cậu học tốt!