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1/4.12/13+1/4.1/13-3/25
1/4.(12/13+1/13)-3/25
1/4.1-3/25
1/4-3/25
1/8
\(\frac{1}{4}\cdot\frac{12}{13}+\frac{1}{4}\cdot\frac{1}{13}-12\%=\frac{1}{4}\cdot\frac{12}{13}+\frac{1}{4}\cdot\frac{1}{13}-\frac{3}{25}=\frac{1}{4}\cdot\left(\frac{12}{13}+\frac{1}{13}\right)-\frac{3}{25}\)
\(=\frac{1}{4}\cdot1-\frac{3}{25}=\frac{1}{4}-\frac{3}{25}=\frac{13}{100}\)
Nhớ bài đây sửa đi sửa lại cũng vì do cái số " % " :(((
a) \(\left|\frac{2}{5}:x\right|=\frac{1}{4}\)
Trường hợp 1 : \(\frac{2}{5}\) : x = \(\frac{1}{4}\)
=> x = \(\frac{2}{5}:\frac{1}{4}=\frac{2}{5}\cdot4=\frac{8}{5}\)
Trường hợp 2 : \(\frac{2}{5}:x=-\frac{1}{4}\)
=> \(x=\frac{2}{5}:\left(-\frac{1}{4}\right)=\frac{2}{5}\cdot\left(-4\right)=-\frac{8}{5}\)
Vậy \(x=\pm\frac{8}{5}\)
b) \(\frac{x}{24}=-\frac{1}{3}-\frac{1}{8}=-\frac{11}{24}\)
=> x = -11
c) \(\frac{3}{x+3}=\frac{-7}{21}\)
=> \(\frac{3}{x+3}=\frac{-1}{3}\)
=> -1(x + 3) = 9
=> -x - 3 = 9
=> -x = 12
=> x = -12
a)15/8+3/4-5/12
=45+18-10/24
=53/24
b)11/24.12/33+5/6
=11.12/12.2.11.3+5/6
=1/6+5/6
=6/6=1
c)15/8+7/24:5/8
=15/8+7/24.8/5
=15/8+7.8/3.8.5
=15/8+7/15
=đề sai, nếu đúng thì như này
=8/15+7/15
=15/15=1
a) \(3x-10=2x+13\Leftrightarrow x=13+10=23\)
b) \(x+12=-5-x\Leftrightarrow2x=-17\Leftrightarrow x=-\frac{17}{2}\)
c) \(x+5=10-x\Leftrightarrow2x=5\Leftrightarrow x=\frac{5}{2}\)
d) \(6x+23=2x-12\Leftrightarrow4x=-35\Leftrightarrow x=-\frac{35}{4}\)
e) \(12-x=x+1\Leftrightarrow2x=11\Leftrightarrow x=\frac{11}{2}\)
f) \(14+4x=3x+20\Leftrightarrow x=20-14=6\)
g) \(2\left(x-1\right)+3\left(x-2\right)=x-4\Leftrightarrow2x-2+3x-6=x-4\)
\(\Leftrightarrow5x-8=x-4\Leftrightarrow4x=4\Leftrightarrow x=1\)
h ) \(3\left(4-x\right)-2\left(x-1\right)=x+20\Leftrightarrow12-3x-2x+2=x+20\)
\(\Leftrightarrow14-5x=x+20\Leftrightarrow6x=-6\Leftrightarrow x=-1\)
i ) \(4\left(2x+7\right)-3\left(3x-2\right)=24\Leftrightarrow8x+28-9x+6=24\)
\(\Leftrightarrow34-x=24\Leftrightarrow x=34-24=10\)
k) \(3\left(x-2\right)+2x=10\Leftrightarrow3x-6+2x=5x-6=10\)
\(\Leftrightarrow5x=10+6=16\Leftrightarrow x=\frac{16}{5}\)
Tự KL cho các phần
a; \(\dfrac{x}{8}\) = \(\dfrac{3}{4}\) + \(\dfrac{-5}{8}\)
\(\dfrac{x}{8}\) = \(\dfrac{1}{8}\)
\(x\) = \(\dfrac{1}{8}\) \(\times\) 8
\(x\) = 1
b; \(\dfrac{x}{12}\) = \(\dfrac{3}{4}\) + \(\dfrac{-2}{3}\)
\(\dfrac{x}{12}\) = \(\dfrac{1}{12}\)
\(x\) = \(\dfrac{1}{12}\) \(\times\) 12
\(x\) = 1
c; 1 + \(\dfrac{11}{3}\) = \(\dfrac{24}{x}\)
\(\dfrac{14}{3}\) = \(\dfrac{24}{x}\)
\(x\) = 24 : \(\dfrac{14}{3}\)
\(x\) = \(\dfrac{36}{7}\)
d; \(\dfrac{x}{6}\) - \(\dfrac{3}{4}\) = \(\dfrac{1}{12}\)
\(\dfrac{x}{6}\) = \(\dfrac{1}{12}\) + \(\dfrac{3}{4}\)
\(\dfrac{x}{6}\) = \(\dfrac{5}{6}\)
\(x\) = \(\dfrac{5}{6}\) \(\times\) 6
\(x\) = 5
\(\dfrac{8}{9}\) : ( 2 - 3 \(\times\) y) = \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{9}\) : \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{15}\)
3 \(\times\) y = 2 - \(\dfrac{8}{15}\)
3 \(\times\) y = \(\dfrac{22}{15}\)
y = \(\dfrac{22}{15}\) : 3
y = \(\dfrac{22}{45}\)
1/ -7264 + (1543 + 7264)
=-7264 + 1543 + 7264=1543
2/ (144 – 97) – 144
=144-97-144=-97
3/ (-145) – (18 – 145)(Vì có dấu trừ ở trước ngoặc nên p đổi dấu)
=-145-18+145=-18
4/ 111 + (-11 + 27)
=111-11+27=137
Bài 1:
1: =-5/24+16/27+3/4
=-5/24+18/24+16/27
=13/24+16/27
=117/216+128/216=245/216
2: =-1/3+1/3+6/7=6/7
3: \(=\dfrac{1}{2}-\dfrac{7}{12}+\dfrac{1}{2}=1-\dfrac{7}{12}=\dfrac{5}{12}\)
4: \(=-\dfrac{5}{8}+\dfrac{14}{25}-\dfrac{6}{10}=\dfrac{-125+112-120}{200}=\dfrac{-133}{200}\)
ban lam sai rui de mk lam lai nhe.
\(12.\left(x-1\right):3=4^3-2^3\)
\(12.\left(x-1\right):3=64-8\)
\(12.\left(x-1\right):3=56\)
\(12.\left(x-1\right)=56.3\)
\(12.\left(x-1\right)=168\)
\(x-1=168:12\)
\(x-1=14\)
\(x=15\)
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