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19 tháng 9
d: \(\frac27-\left(\frac23+2x\right)=\frac57\)
=>\(2x+\frac23=\frac27-\frac57=-\frac37\)
=>\(2x=-\frac37-\frac23=-\frac{9}{21}-\frac{14}{21}=-\frac{23}{21}\)
=>\(x=-\frac{23}{21}:2=-\frac{23}{42}\)
e: \(\frac12-2x=\left(-\frac12\right)^3\)
=>\(\frac12-2x=-\frac18\)
=>\(2x=\frac12+\frac18=\frac58\)
=>\(x=\frac58:2=\frac{5}{16}\)
f: \(\left(2x-3\right)\left(\frac34x+1\right)=0\)
=>\(\left[\begin{array}{l}2x-3=0\\ \frac34x+1=0\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=3\\ \frac34x=-1\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac32\\ x=-\frac43\end{array}\right.\)
g: \(\frac{7}{12}-\left(x+\frac76\right):\frac65=-\frac54\)
=>\(\left(x+\frac76\right):\frac65=\frac{7}{12}+\frac54=\frac{7}{12}+\frac{15}{12}=\frac{22}{12}=\frac{11}{6}\)
=>\(x+\frac76=\frac{11}{6}\cdot\frac65=\frac{11}{5}\)
=>\(x=\frac{11}{5}-\frac76=\frac{66}{30}-\frac{35}{30}=\frac{31}{30}\)
h: \(\frac34:\left(x+\frac12\right)-\frac56=-\frac14\)
=>\(\frac34:\left(x+\frac12\right)=-\frac14+\frac56=-\frac{3}{12}+\frac{10}{12}=\frac{7}{12}\)
=>\(x+\frac12=\frac34:\frac{7}{12}=\frac34\cdot\frac{12}{7}=\frac{36}{28}=\frac97\)
=>\(x=\frac97-\frac12=\frac{18}{14}-\frac{7}{14}=\frac{11}{14}\)
i: \(\frac25x+\frac35x=\frac34\)
=>\(x\left(\frac25+\frac35\right)=\frac34\)
=>\(x\cdot\frac55=\frac34\)
=>\(x=\frac34\)
k: \(\frac12x+\frac23x-x=\frac13\)
=>\(x\left(\frac12+\frac23-1\right)=\frac13\)
=>\(x\left(\frac12-\frac13\right)=\frac13\)
=>\(x\cdot\frac16=\frac13\)
=>\(x=\frac13:\frac16=2\)
l: \(\left(\frac32-\frac{2}{-5}\right):x-\frac12=\frac32\)
=>\(\left(\frac32+\frac25\right):x=\frac32+\frac12=2\)
=>\(\left(\frac{15}{10}+\frac{4}{10}\right):x=2\)
=>\(\frac{19}{10}:x=2\)
=>\(x=\frac{19}{10}:2=\frac{19}{20}\)
m: \(\left(5x-1\right)\left(2x-\frac13\right)=0\)
=>\(\left[\begin{array}{l}5x-1=0\\ 2x-\frac13=0\end{array}\right.\Rightarrow\left[\begin{array}{l}5x=1\\ 2x=\frac13\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac15\\ x=\frac16\end{array}\right.\)
20 tháng 9
Bài 3:
a: \(A=3^2\cdot\frac{1}{243}\cdot81^2\cdot\frac{1}{3^3}\)
\(=\frac{9}{243}\cdot81\cdot81\cdot\frac{1}{27}\)
\(=\frac{1}{27}\cdot81\cdot3=3\cdot3=9\)
b: \(B=\left(4\cdot2^5\right):\left(2^3\cdot\frac{1}{16}\right)\)
\(=2^2\cdot2^5:\left(\frac{2^3}{16}\right)=2^7:\frac12=2^7\cdot2=2^8=256\)
Bài 2:
a: \(A=\left(3^2\right)^2-\left(-2^3\right)^2-\left(-5^2\right)^2\)
\(=3^4-2^6-\left(-25\right)^2\)
=81-64-625
=17-625
=-608
b: \(B=2^3+3\cdot\left(\frac12\right)^0\cdot\left(\frac12\right)^2\cdot4+\left\lbrack\left(-2\right)^2:\frac12\right\rbrack:8\)
\(=8+3\cdot1\cdot\frac14\cdot4+4\cdot\frac28\)
=8+3+1
=11+1
=12
Bài 1:
a: \(\left(\frac23\right)^3\cdot\left(-\frac34\right)^2\cdot\left(-1\right)^5:\left(\frac25\right)^2\cdot\left(-\frac{5}{12}\right)^2\)
\(=\frac{2^3}{3^3}\cdot\frac{3^2}{4^2}\cdot\left(-1\right):\frac{4}{25}\cdot\frac{25}{144}\)
\(=\frac{2^3}{2^4}\cdot\frac13\cdot\left(-1\right)\cdot\frac{25}{4}\cdot\frac{25}{144}=\frac16\cdot\left(-1\right)\cdot\frac{625}{576}=\frac{-625}{3456}\)
b:Sửa đề: \(\frac{\left(6^6+6^3\cdot3^3+3^6\right)}{-73}\)
\(=\frac{3^6\cdot2^6+3^6\cdot2^3+3^6}{-73}\)
\(=\frac{3^6\left(2^6+2^3+1\right)}{-73}=\frac{3^6\cdot73}{-73}=-3^6=-729\)
21 tháng 9
Bài 4:
Ta có: \(\hat{M_2}=\hat{N_2}\left(=60^0\right)\)
mà hai góc này là hai góc ở vị trí đồng vị
nên a//b
Bài 3:
a//b
a⊥BA
Do đó: b⊥BA
=>\(\hat{ABC}=90^0\)
AD//BC
=>\(\hat{ADC}+\hat{DCB}=180^0\)
=>\(\hat{ADC}=180^0-110^0=70^0\)
Bài 2:
a: \(-\frac35+\frac{-2}{5}:x=\frac13\)
=>\(-\frac25:x=\frac13+\frac35=\frac{5}{15}+\frac{9}{15}=\frac{14}{15}\)
=>\(x=-\frac25:\frac{14}{15}=-\frac25\cdot\frac{15}{14}=-\frac37\)
b: \(0,2+\left|x-1,3\right|=1,5\)
=>|x-1,3|=1,5-0,2=1,3
=>\(\left[\begin{array}{l}x-1,3=1,3\\ x-1,3=-1,3\end{array}\right.\Rightarrow\left[\begin{array}{l}x=2,6\\ x=0\end{array}\right.\)
c: \(\left(\frac37-2x\right)^2=\frac49\)
=>\(\left[\begin{array}{l}\frac37-2x=\frac23\\ \frac37-2x=-\frac23\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=\frac37-\frac23=\frac{9}{21}-\frac{14}{21}=-\frac{5}{21}\\ 2x=\frac37+\frac23=\frac{9}{21}+\frac{14}{21}=\frac{23}{21}\end{array}\right.\)
=>\(\left[\begin{array}{l}x=-\frac{5}{21}:2=-\frac{5}{42}\\ x=\frac{23}{21}:2=\frac{23}{42}\end{array}\right.\)
d: \(2^{x}+2^{x+3}=144\)
=>\(2^{x}+2^{x}\cdot2^3=144\)
=>\(2^{x}\left(1+2^3\right)=144\)
=>\(2^{x}\cdot9=144\)
=>\(2^{x}=\frac{144}{9}=16=2^4\)
=>x=4
Bài 1:
a: \(\frac{14}{57}+\frac{29}{23}-\frac{71}{57}+\frac{-6}{23}\)
\(=\left(\frac{14}{57}-\frac{71}{57}\right)+\left(\frac{29}{23}-\frac{6}{23}\right)\)
\(=\frac{-57}{57}+\frac{23}{23}=-1+1=0\)
b: \(\frac{5}{12}\cdot\left(-\frac34\right)+\frac{7}{12}\left(-\frac34\right)\)
\(=-\frac34\left(\frac{5}{12}+\frac{7}{12}\right)=-\frac34\cdot\frac{12}{12}=-\frac34\)
d: \(\left(-\frac{3}{11}:\frac{5}{22}\right)\cdot\left(-\frac{15}{3}:\frac{26}{3}\right)\)
\(=-\frac{3}{11}\cdot\frac{22}{5}\cdot\left(_{}-5\right)\cdot\frac{3}{26}=-\frac35\cdot\left(-5\right)\cdot2\cdot\frac{3}{26}=3\cdot2\cdot\frac{3}{26}=\frac{9}{13}\)
f: \(\frac{9^{15}\cdot8^{11}}{3^{29}\cdot16^8}=\frac{3^{30}}{3^{29}}\cdot\frac{2^{33}}{2^{32}}=3\cdot2=6\)
bn lôi bài toán 6 hoặc lớp 5 ra đây hỏi bài à bn đây là chỗ hỏi bài dành cho hc sinh lớp 7 mà bn
sos m cần gấp