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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
\(10,\frac{3+5x}{5}-3=\frac{9x-3}{4}\)
\(\Leftrightarrow\frac{3+5x-15}{5}=\frac{9x-3}{4}\)
\(\Leftrightarrow\frac{-12+5x}{5}=\frac{9x-3}{4}\)
\(\Leftrightarrow\left(-12+5x\right)5=\left(9x-3\right)4\)
\(\Leftrightarrow-60+25x=36x-12\)
\(\Leftrightarrow26x-36x=-12+60\)
\(\Leftrightarrow-10x=48\)
\(\Leftrightarrow x=-4,8\)
\(a,-5x\left(x-3\right)\left(2x+4\right)-\left(x+3\right)\left(x-3\right)+\left(5x-2\right)\left(3x+4\right)\)
\(=-5x\left(2x^2-x-12\right)-\left(x^2-9\right)+15x^2+20x-6x-8\)
\(=-10x^3+5x^2+60x-x^2+9+15x^2+20x-6x-8\)
\(=-10x^3+19x^2+74x+1\)
\(b,\left(4x-1\right)x\left(3x+1\right)-5x^2.x\left(x-3\right)-\left(x-4\right)x\left(x-5\right)\)\(-7\left(x^3-2x^2+x-1\right)\)
\(=\left(4x^2-x\right)\left(3x+1\right)-5x^4-15x^3-\left(x^2-4x\right)\left(x-5\right)\)\(-7x^3+14x^2-7x+7\)
\(=12x^3+x^2-x-5x^4-15x^3-x^3+9x^2+20x\)\(-7x^3+14x^2-7x+7\)
\(=-5x^4-11x^3+24x^2+12x+7\)
\(c,\left(5x-7\right)\left(x-9\right)-\left(3-x\right)\left(2-5x\right)-2x\left(x-4\right)\)
\(=5x^2-52x+63-6+17x-5x^2-2x^2+8x\)
\(=-2x^2-27x+57\)
\(d,\left(5x-4\right)\left(x+5\right)-\left(x+1\right)\left(x^2-6\right)-5x+19\)
\(=5x^2+21x-20-x^3-x^2+6x+6-5x+19\)
\(=-x^3+4x^2+22x+5\)
\(e,\left(9x^2-5\right)\left(x-3\right)-3x^2\left(3x+9\right)-\left(x-5\right)\left(x+4\right)-9x^3\)
\(=9x^3-27x^2-5x+15-9x^3-27x^2-x^2+x+20-9x^3\)
\(=-9x^3-55x^2+4x+35\)
\(g,\left(x-1\right)^2-\left(x+2\right)^2\)
\(=x^2-2x+1-x^2-4x-4\)
\(=-6x-3\)
một đòn bẫy dài một mét .đặt ở đâu để có thể dùng 3600n có thể nâng tảng đá nặng 120kg?
+) (5x-1). (2x+3)-3. (3x-1)=0
10x^2+15x-2x-3 - 9x+3=0
10x^2 +8x=0
2x(5x+4)=0
=> x=0 hoặc x= -4/5
+) x^3 (2x-3)-x^2 (4x^2-6x+2)=0
2x^4 -3x^3 -4x^4 + 6x^3 - 2x^2=0
-2x^4 + 3x^3-2x^2=0
x^2(-2x^2+x-2)=0
-2x^2(x-1)^2=0
=> x=0 hoặc x=1
+) x (x-1)-x^2+2x=5
x^2 -x -x^2+2x=5
x=5
+) 8 (x-2)-2 (3x-4)=25
8x - 16-6x+8=25
2x=33
x=33/2
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