Tìm X, biết:
\(\frac{2x+3}{5x+2}=\frac{4x+5}{10x+2}\)
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\(\frac{2x+3}{5x+2}=\frac{4x+5}{10x+2}\left(DK:x\ne-\frac{2}{5};x\ne-\frac{1}{5}\right)\)
\(\Rightarrow\left(2x+3\right)\left(10x+2\right)=\left(4x+5\right)\left(5x+2\right)\Rightarrow20x^2+34x+6=20x^2+33x+10\Rightarrow x=4\)(thoả mãn)
Vậy x = 4
\(\frac{2x+3}{5x+2}=\frac{4x+5}{10x+2}\)
\(\Leftrightarrow\left(2x+3\right)\left(10x+2\right)=\left(5x+2\right)\left(4x+5\right)\)
\(\Leftrightarrow2x\left(10x+2\right)+3\left(10x+2\right)=5x\left(4x+5\right)\)
\(\Leftrightarrow20x^2+4x+20x+6=20x^2+25x+9x+10\)
\(\Leftrightarrow20x^2+4x+20x+6-\left(20x^2+25x+9x+10\right)=0\)\(\Rightarrow20x^2+24x+6-\left(20x^2+34x+10\right)=0\)
\(\Leftrightarrow-10x-4=0\)
\(\Leftrightarrow-10x=4\)
\(\Leftrightarrow x=-\frac{4}{10}\)
a: =>-x+2x=3-7
=>x=-4
b: =>6x+2+2x-5=0
=>8x-3=0
hay x=3/8
c: =>5x+2x-2-4x-7=0
=>3x-9=0
hay x=3
d: =>10x2-10x2-15x=15
=>-15x=15
hay x=-1
\(\frac{x-1}{2}=\frac{y-2}{3}=\frac{z-3}{4}\Rightarrow\frac{2x-2}{4}=\frac{3y-6}{6}=\frac{z-3}{4}\)
Áp dụng tính chất của dãy tỉ số bằng nhau ta có:
\(\frac{2x-2}{4}=\frac{3y-6}{6}=\frac{z-3}{4}=\frac{\left(2x-2\right)+\left(3y-6\right)-\left(z-3\right)}{4+6-4}=\frac{2x-2+3y-6-z+3}{4+6-4}\)
\(=\frac{\left(2x+3y-z\right)+\left(-2+6+3\right)}{6}=\frac{50+\left(-5\right)}{6}=\frac{45}{6}=7,5\)
\(\frac{x-1}{2}=7,5\Rightarrow x-1=15\Rightarrow x=16\)
\(\frac{y-2}{3}=7,5\Rightarrow y-2=24,5\Rightarrow y=20,5\)
\(\frac{z-3}{4}=7,5\Rightarrow z-3=30\Rightarrow z=33\)
\(5X\left(X-2020\right)+X=2020\)
\(\Leftrightarrow5X^2-10100X+X=2020\)
\(\Leftrightarrow5X^2-10099X=2020\)
\(\Leftrightarrow5X^2-10099X-2020=0\)
\(\Leftrightarrow5X^2-10100X+x-2020=0\)
\(\Leftrightarrow5X\left(X-2020\right)+X-2020=0\)
\(\Leftrightarrow\left(X-2020\right)\left(5X+1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2020\\x=-\frac{1}{5}\end{cases}}\)
\(4\left(x-5\right)^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)\right]^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)-2x-1\right]\left[2\left(x-5\right)+2x+1\right]=0\)
\(\Leftrightarrow\left(2x-10-2x-1\right)\left(2x-10+2x+1\right)=0\)
\(\Leftrightarrow-11\left(4x-9\right)=0\)
\(\Leftrightarrow x=\frac{9}{4}\)
x+2/327 + x+3/326 + x+4/325 + x+5/324 + x+349/5 = 0
=> x+2/327 + 1 + x+3/326 + 1 + x+4/325 + 1 + x+5/324 + 1 - x+349/5 - 4 = 0
=> x+329/327 + x+329/326 + x+329/325 + x+329/324 + x+329/5 = 0
=> (x+329).(1/327 + 1/326 + 1/325 + 1/324 + 1/5) = 0
Dễ thấy: 1/327 + 1/326 + 1/325 + 1/324 + 1/5 > 0
=> x + 329 = 0
=> x = -329
Ta có: \(\frac{2x+3}{5x+2}=\frac{4x+5}{10x+2}\)
\(\Rightarrow\left(2x+3\right).\left(10x+2\right)=\left(5x+2\right).\left(4x+5\right)\)
\(\Rightarrow20x^2+4x+30x+6=10x^2+25x+8x+10\)
\(\Rightarrow34x+6=33x+10\)
\(\Rightarrow34x-33x=-6+10\)
\(\Rightarrow x=4\)
Ta có:
\(\frac{2x+3}{5x+2}=\frac{4x+5}{10x+2}\)
\(\Rightarrow\left(2x+3\right)\left(10x+2\right)=\left(5x+2\right)\left(4x+5\right)\)
\(\Rightarrow20x^2+34x+6=20x^2+33x+10\)
\(\Rightarrow\left(20x^2+34x+6\right)-\left(20x^2+33x+6\right)=\left(20x^2+33x+10\right)-\left(20x^2+33x+6\right)\)
\(\Rightarrow\left(20x^2-20x^2\right)+\left(34x-33x\right)+\left(6-6\right)=\left(20x^2-20x^2\right)+\left(33x-33x\right)+\left(10-6\right)\)
\(\Rightarrow x=4\)
Vậy x = 4.