1+2+3+4+5+...+x=378
tìm x
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a: =>x-2/5=3/4:1/3=3/4*3=9/4
=>x=9/4+2/5=45/20+8/20=53/20
b: =>x-2/3=7/3:4/5=7/3*5/4=35/12
=>x=35/12+2/3=43/12
c: 1/3(x-2/5)=4/5
=>x-2/5=4/5*3=12/5
=>x=12/5+2/5=14/5
d: =>2/3x-1/3-1/4x+1/10=7/3
=>5/12x-7/30=7/3
=>5/12x=7/3+7/30=77/30
=>x=77/30:5/12=154/25
e: \(\Leftrightarrow x\cdot\dfrac{3}{7}-\dfrac{2}{7}+\dfrac{1}{2}-\dfrac{5}{4}x+\dfrac{5}{2}=0\)
=>\(x\cdot\dfrac{-23}{28}=\dfrac{2}{7}-3=\dfrac{-19}{7}\)
=>x=19/7:23/28=76/23
f: =>1/2x-3/2+1/3x-4/3+1/4x-5/4=1/5
=>13/12x=1/5+3/2+4/3+5/4=257/60
=>x=257/65
i: =>x^2-2/5x-x^2-2x+11/4=4/3
=>-12/5x=4/3-11/4=-17/12
=>x=17/12:12/5=85/144
1: \(\frac{3x-2}{3}-2=\frac{4x+1}{4}\)
=>\(\frac{3x-2-6}{3}=\frac{4x+1}{4}\)
=>\(\frac{3x-8}{3}=\frac{4x+1}{4}\)
=>3(4x+1)=4(3x-8)
=>12x+3=12x-32
=>3=-32(vô lý)
=>Phương trình vô nghiệm
2: \(\frac{x-3}{4}+\frac{2x-1}{3}=\frac{2-x}{6}\)
=>\(\frac{3\left(x-3\right)+4\left(2x-1\right)}{12}=\frac{2\left(2-x\right)}{12}\)
=>3(x-3)+4(2x-1)=2(2-x)
=>3x-9+8x-4=4-2x
=>11x-13=4-2x
=>13x=17
=>\(x=\frac{17}{13}\)
3: \(\frac12\left(x+1\right)+\frac14\left(x+3\right)=3-\frac13\left(x+2\right)\)
=>\(\frac12x+\frac12+\frac14x+\frac34+\frac13x+\frac23=3\)
=>\(x\left(\frac12+\frac14+\frac13\right)+\frac{6}{12}+\frac{9}{12}+\frac{8}{12}=3\)
=>\(x\left(\frac{6}{12}+\frac{3}{12}+\frac{4}{12}\right)=3-\frac{23}{12}=\frac{36}{12}-\frac{23}{12}=\frac{13}{12}\)
=>\(x\cdot\frac{13}{12}=\frac{13}{12}\)
=>x=1
4: \(\frac{x+4}{5}-x+4=\frac{x}{3}-\frac{x-2}{2}\)
=>\(\frac{x+4}{5}+\frac{5\left(-x+4\right)}{5}=\frac{2x-3\left(x-2\right)}{6}\)
=>\(\frac{x+4-5x+20}{5}=\frac{2x-3x+6}{6}\)
=>\(\frac{-4x+24}{5}=\frac{-x+6}{6}\)
=>6(-4x+24)=5(-x+6)
=>-24x+144=-5x+30
=>-19x=-114
=>x=6
5: \(\frac{4-5x}{6}=\frac{2\left(-x+1\right)}{2}\)
=>\(\frac{4-5x}{6}=-x+1\)
=>6(-x+1)=-5x+4
=>-6x+6=-5x+4
=>-6x+5x=4-6
=>-x=-2
=>x=2
6: \(-\left(\frac{x-3}{2}-2\right)=\frac{5\left(x+2\right)}{4}\)
=>\(-\frac{x-3-4}{2}=\frac{5\left(x+2\right)}{4}\)
=>\(\frac{-2\left(x-7\right)}{4}=\frac{5\left(x+2\right)}{4}\)
=>5(x+2)=-2(x-7)
=>5x+10=-2x+14
=>7x=4
=>x=4/7
7: \(\frac{2\left(2x+1\right)}{5}-\frac{6+x}{3}=\frac{5-4x}{15}\)
=>\(\frac{6\left(2x+1\right)-5\left(x+6\right)}{15}=\frac{5-4x}{15}\)
=>6(2x+1)-5(x+6)=-4x+5
=>12x+6-5x-30=-4x+5
=>7x-24=-4x+5
=>7x+4x=5+24
=>11x=29
=>\(x=\frac{29}{11}\)
8: \(\frac{7-3x}{2}-\frac{5+x}{5}=1\)
=>\(\frac{5\left(7-3x\right)-2\left(x+5\right)}{10}=1\)
=>5(7-3x)-2(x+5)=10
=>35-15x-2x-10=10
=>-17x+25=10
=>-17x=-15
=>x=15/17
Bạn cần viết đề bài bằng công thức toán để được hỗ trợ tốt hơn.
a: \(\dfrac{x+5}{x-1}+\dfrac{8}{x^2-4x+3}=\dfrac{x+1}{x-3}\)
=>(x+5)(x-3)+8=x^2-1
=>x^2+2x-15+8=x^2-1
=>2x-7=-1
=>x=3(loại)
b: \(\dfrac{x-4}{x-1}-\dfrac{x^2+3}{1-x^2}+\dfrac{5}{x+1}=0\)
=>(x-4)(x+1)+x^2+3+5(x-1)=0
=>x^2-3x-4+x^2+3+5x-5=0
=>2x^2+2x-6=0
=>x^2+x-3=0
=>\(x=\dfrac{-1\pm\sqrt{13}}{2}\)
e: =>x^2-2x+1+2x+2=5x+5
=>x^2+3=5x+5
=>x^2-5x-2=0
=>\(x=\dfrac{5\pm\sqrt{33}}{2}\)
g: (x-3)(x+4)*x=0
=>x=0 hoặc x-3=0 hoặc x+4=0
=>x=0;x=3;x=-4
Nhiều vậy ai làm hết được :P
1) \(\frac{3x-2}{3}-2=\frac{4x+1}{4}\)
\(\Leftrightarrow\frac{3x-8}{3}=\frac{4x-1}{4}\)
\(\Leftrightarrow4\left(3x-8\right)=3\left(4x-1\right)\)
\(\Leftrightarrow12x-32=12x-3\)(vô lí)
Vậy pt vô nghiệm
P/s: mấy câu sau tương tự thôi mà :)))
nhăm nhe 1 câu thôi
\(10,\frac{3+5x}{5}-3=\frac{9x-3}{4}\)
\(\Leftrightarrow\frac{3+5x-15}{5}=\frac{9x-3}{4}\)
\(\Leftrightarrow\frac{-12+5x}{5}=\frac{9x-3}{4}\)
\(\Leftrightarrow\left(-12+5x\right)5=\left(9x-3\right)4\)
\(\Leftrightarrow-60+25x=36x-12\)
\(\Leftrightarrow26x-36x=-12+60\)
\(\Leftrightarrow-10x=48\)
\(\Leftrightarrow x=-4,8\)
a: x*3/4=1/5
=>x=1/5:3/4=1/5*4/3=4/15
b: x*3/7=2/5
=>x=2/5:3/7=2/5*7/3=14/15
c: 1/3+2/9=2/12x
=>1/6x=3/9+2/9=5/9
=>x=5/9*6=30/9=10/3
d: 4/15*x-2/3=1/5
=>4/15*x=2/3+1/5=10/15+3/15=13/15
=>4x=13
=>x=13/4
e: x:1/7=2/3
=>x=2/3*1/7=2/21
f: 1/9:x=7/3
=>x=1/9:7/3=1/9*3/7=3/63=1/21
j: 1/4+5/12=8/3:x
=>8/3:x=3/12+5/12=8/12=2/3
=>x=4
h: =>7/4:x=1/5+1/2=7/10
=>x=7/4:7/10=10/4=5/2
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1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
đáng lẽ phải chứng minh 2+2^2+2^3+2^4+...+2^99+2^100 chia hết cho mấy hoặc ...
tick cho mik nha