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\(\frac{1}{3}:x-\frac{2}{3}=\frac{5}{6}+\frac{7}{8}\)
\(\frac{1}{3}:x-\frac{2}{3}=\frac{41}{24}\)
\(\frac{1}{3}:x=\frac{19}{8}\)
\(x=\frac{8}{57}\)
\(\frac{2}{5}-x:\frac{3}{5}=\frac{6}{7}\)
\(x:\frac{3}{5}=\frac{-16}{35}\)
\(x=\frac{-48}{175}\)
\(\frac{4}{5}-\frac{26}{m}=\frac{-8}{15}\)
\(\frac{26}{m}=\frac{4}{3}\)
=> 26 x 3 = m x 4
78 = m x 4
m = 19,5
Câu 1 :\(\frac{1}{3}\div x-\frac{2}{3}=\frac{5}{6}+\frac{7}{8}\)
\(\Leftrightarrow\frac{1}{3x}=\frac{5}{6}+\frac{7}{8}+\frac{2}{3}\)
\(\Leftrightarrow\frac{1}{3x}=\frac{4\cdot5}{24}+\frac{7\cdot3}{24}+\frac{2\cdot8}{24}\)
\(\Leftrightarrow\frac{1}{3x}=\frac{20}{24}+\frac{21}{24}+\frac{16}{24}\)
\(\Leftrightarrow\frac{1}{3x}=\frac{57}{24}\)
\(\Leftrightarrow24=57\cdot3x\)
\(\Leftrightarrow24=171x\)
\(\Leftrightarrow x=\frac{24}{171}=\frac{8}{57}\)
Câu 2: \(\frac{2}{5}-x\div\frac{3}{5}=\frac{6}{7}\)
\(\Leftrightarrow\frac{-5x}{3}=\frac{6}{7}-\frac{2}{5}\)
\(\Leftrightarrow\frac{-5x}{3}=\frac{5\cdot6}{35}-\frac{2\cdot7}{35}\)
\(\Leftrightarrow\frac{-5x}{3}=\frac{30}{35}-\frac{14}{35}\)
\(\Leftrightarrow-\frac{5x}{3}=\frac{16}{35}\)
\(\Leftrightarrow-175x=48\)
\(\Leftrightarrow x=-\frac{48}{175}\)
Câu 3: \(\frac{4}{5}-\frac{26}{m}=-\frac{8}{15}\)
\(\Leftrightarrow\frac{26}{m}=\frac{4}{5}-\left(-\frac{8}{15}\right)\)
\(\Leftrightarrow\frac{26}{m}=\frac{4}{5}+\frac{8}{15}\)
\(\Leftrightarrow\frac{26}{m}=\frac{12}{15}+\frac{8}{15}\)
\(\Leftrightarrow\frac{26}{m}=\frac{20}{15}\)
\(\Leftrightarrow20m=26\cdot15=390\)
\(\Leftrightarrow m=\frac{390}{20}=\frac{39}{2}\)
Câu 1:
a) 2(x-3)-3(x-5)=4(3-x)-18
<=> 3x-6-3x+15-12+4x+18=0
<=> 4x+15=0
<=> 4x=-15
<=> x=-15/4
b) -2(2x-8)+3(4-2x)=-57-5(3x-7)
<=> -4x+16+12-6x+57+15x-35=0
<=> -5x+50=0
<=> -5x=-50
<=> x=10
c) 3|2x2-7|=33
<=> |2x2-7|=11
<=> \(\orbr{\begin{cases}2x^2-7=11\\2x^2-7=-11\end{cases}\Leftrightarrow\orbr{\begin{cases}2x^2=18\\2x^2=-4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x^2=9\\x^2=-2\end{cases}\Leftrightarrow}x=\pm3}\)
d) có 9x+17=3(3x+2)+11
=> 11 chia hết cho 3x+2
=> 3x+2 thuộc Ư (11)={-11;-1;1;11}
ta có bảng
| 3x+2 | -11 | -1 | 1 | 11 |
| x | -13/3 | -1 | -1/3 | 3 |
Câu 2:
xy-5x+y=17
<=> x(y-5)+(y-5)=12
<=> (y-5)(x+5)=12
=> y-5; x+5 \(\inƯ\left(12\right)=\left\{-12;-6;-4;-3;-2;-1;1;2;3;4;6;12\right\}\)
lập bảng tương tự câu 1
câu 1 bỏ dấu ngoặc rồi tính
( 36 + 79 ) + ( 145 _ 79 _ 36 )
\(=36+79+145-79-36\)
\(=\left(36-36\right)+\left(79-79\right)+145\)\
\(=0+0+145=145\)
10 _ [ 12 _ ( -9 _ 1 ) ]
\(=10-12-10\)
\(=10-10-12\)
\(=0-12=-12\)
( 38 _ 29 + 43) _ ( 43 + 38 )
\(=38-29+43-43-38\)
\(=\left(38-38\right)+\left(43-43\right)-29\)
\(=0+0-29=-29\)
271 _ [ ( -43 ) + 271 _ ( -17 ) ]
\(=271+43-271-17\)
\(=\left(271-271\right)+\left(43-17\right)\)
\(=0+26=26\)
- 144 _ [ 29 _ ( + 144 ) _ ( + 144 )]
\(=-144-19+144+144\)
\(=\left(-144+144+144\right)-19\)
\(=144-19=125\)
đợi mk lm tiếp câu 2 nha .
bài 2 tính tổng các số nguyên
- 18 < hoặc bằng x < hoặc bằng 17
\(\Rightarrow x\in\left\{-18;-17;-16;....;17\right\}\)
tổng \(x=-18+\left(-17\right)+\left(-16\right)+...+17=-18\)
- 27 < hoặc bằng x < hoặc bằng 27
\(\Rightarrow x\in\left\{-27;-26;-25;..;27\right\}\)
Tổng \(x=-27+\left(-26\right)+\left(-25\right)+...+27=0\)
Câu 1:
\(\frac{2x-1}{3}=\frac{3x+1}{4}\)
\(\frac{8x-4}{12}=\frac{9x+3}{12}\)
\(\Rightarrow8x-4=9x+3\)
\(8x-9x=3+4\)
\(-x=7\Rightarrow x=-7\)
Câu 2:
\(\frac{3x}{5x+4}=\frac{12}{28}\)
\(\Rightarrow\left(3x\right).28=12.\left(5x+4\right)\)
\(84x=60x+48\)
\(84x-60x=48\)
\(24x=48\)
\(\Leftrightarrow x=2\)
Câu 3 :
\(\frac{x}{2}=\frac{8}{x}\)
\(\Rightarrow x.x=8.2\)
\(x^2=16\)
\(x^2=\left(\pm4\right)^2\)
\(\Rightarrow x\left\{-4;4\right\}\)
học tốt !!!
Câu 1: \(\frac{2x-1}{3}=\frac{3x+1}{4}\)
\(\Leftrightarrow2\left(2x-1\right)=3\left(3x+1\right)\)
\(\Leftrightarrow4x-2=9x+3\)
<=> -9x+4x=3+2
<=> -5x=5
<=> x=-1
Câu 3: \(\frac{x}{2}=\frac{8}{x}\left(x\ne0\right)\)
<=> x2=16
<=> \(\orbr{\begin{cases}x=4\\x=-4\end{cases}\left(tmđk\right)}\)
Câu 2: Bạn cũng nhân chéo lên nhưng nhớ đi điều kiện: \(x\ne\frac{-4}{5}\)
Con " Nguyễn Huyền Trang " đéo biết thì trả lời làm cái l*n gì
Câu 13 :
\(\left(-\frac{1}{4}+\frac{5}{8}\right)+-\frac{3}{5}\)
\(=\frac{3}{8}-\frac{-3}{5}\)
\(=\frac{39}{40}\)
Câu 14 :
\(M=\frac{5}{9}.\frac{7}{13}+\frac{5}{9}.\frac{9}{13}-\frac{5}{9}.\frac{3}{13}\)
\(=\frac{5}{9}.\left(\frac{7}{13}+\frac{9}{13}-\frac{3}{13}\right)\)
\(=\frac{5}{9}.1=\frac{5}{9}\)
Câu 15 :
\(E=\left(-\frac{3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
\(E=\left(-\frac{3}{4}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
\(E=0\)
Câu 16 :
\(H=\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}\right)+\frac{7}{8}:\left(\frac{1}{36}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}+\frac{1}{36}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\frac{-7}{24}=-3\)
huhuhuhuhuhuhuhuhuhuhuhuhu giúp mk đi
Plssssssssssssssssssssssssssssssssssssssssssssss
Bài 1.Tính
a) = ( -100 ); b) = ( -55 ); c) = ( -20 ); d) = 3125; e) ( -9 ); g) = ( -24 )
Bài 2. Tính
a) =190; b) = ( -310 ); c) = ( -330 ); d) =102 000; e) = ( -108 ); g) = ( -7 ).
Bài 3.Tính
a) = ( -250 ); b) ( -48 ); c) = ( -16 ); d) = 32; e) ( -3 ); g) = ( -9 ).
Bài 4. Giải
Chị An có: 500.5-600= 1900 đ
Chị Lan có: 500.3-1000= 500 đ
Chị Trang có: 500.6-400= 2600 đ
+ \(72:\left(x-15\right)=8\)
\(x-15=9\)
\(x=24\)
+ \(\dfrac{3}{90}-3x=3\)
\(3\left(\dfrac{1}{90}-x\right)=3\)
\(\dfrac{1}{90}-x=1\)
\(x=\dfrac{1}{90}-1=\dfrac{-89}{90}\)