Tìm x
(2x-5)\(^{x+2}\)- (2x-5)\(^{x+12}\)=0
HỘ MK NHA
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\(\dfrac{-4}{x}=\dfrac{x}{-49}\\ \Rightarrow x^2=\left(-4\right)\left(-49\right)\\ \Rightarrow x^2=196\\ \Rightarrow x=\pm14\)
\(\dfrac{3.6}{x-3}=\dfrac{5}{3}\\ \Rightarrow5\left(x-3\right)=3.3.6\\ \Rightarrow5\left(x-3\right)=54\\ \Rightarrow x-3=\dfrac{54}{5}\\ \Rightarrow x=\dfrac{54}{5}+3\\ \Rightarrow x=\dfrac{69}{15}\)
\(\left(2x+1\right):2=12:3\\ \left(2x+1\right):2=4\\2x+1=2\\ 2x=1\\ x=\dfrac{1}{2} \)
\(\left(2x-14\right):3=12:9\\ \left(2x-14\right):3=\dfrac{4}{3}\\ 2x-14=4\\ 2x=16\\ x=8\)
\(\left(2x-5\right)^2+4\left(3+x\right)\left(x-3\right)-2x=-5\)
\(\Leftrightarrow4x^2-20x+25+4x^2-36-2x=-5\)
\(\Leftrightarrow8x^2-22x-11=-5\Leftrightarrow8x^2-22x-6=0\)
\(\Leftrightarrow2\left(4x^2-11x-3\right)=0\Leftrightarrow2\left[\left(4x^2-12x\right)+\left(x-3\right)\right]=2\left[4x\left(x-3\right)+\left(x-3\right)\right]=0\)
\(\Leftrightarrow2\left(x-3\right)\left(4x+1\right)=0\)
*) x - 3 = 0 <=> x = 3
*) 4x + 1 = 0 <=> x = -1/4
\(\dfrac{x}{x-5}\cdot\left(x^2-2x-15\right)=\dfrac{x\left(x^2-5x+3x-15\right)}{x-5}=\dfrac{x\left(x-5\right)\left(x+3\right)}{x-5}=x\left(x+3\right)\)
\(\frac{7^{x+2}+7^{x+1}+7^x}{57}=\frac{5^{2x}+5^{2x+1}+5^{2x+3}}{131}\)
<=>\(\frac{7^x\left(7^2+7+1\right)}{57}=\frac{5^{2x}.\left(1+5+5^3\right)}{131}\)
<=>\(\frac{7^x.57}{57}=\frac{5^{2x}.131}{131}\)
<=>\(7^x=5^{2x}\)<=>\(7^x=10^x\)<=>x=0
Vậy x=0
1)\(y=\frac{x^2+3x+7}{x+3}=\frac{x\left(x+3\right)+7}{x+3}=x+\frac{7}{x+3}\)= > x +3 thuoc\(U_{\left(7\right)}=\left\{1;-1;7;-7\right\}\)
x thuoc \(\left\{-2;-4;3;-11\right\}\)
2)\(y=\frac{4x+3}{2x+6}=\frac{4x+12-8}{2x+6}=\frac{2\left(2x+6\right)-8}{2x+6}=2-\frac{8}{2x+6}\) =>2x+6 thuoc
\(U_{\left(8\right)}=\left\{1;-1;2;-2;4;-4;8;-8\right\}\)
=>x thuoc \(\left\{-2;-4;-1;-5;1;-7\right\}\)
4)\(y=\frac{4x+1}{3x-1}\)
\(3y=\frac{12x+3}{3x-1}=\frac{12x-4+7}{3x-1}=\frac{4\left(3x-1\right)+7}{3x-1}=4+\frac{7}{3x-1}\)
3x+1 thuoc {1;-1;7;-7}
3x thuoc {0;-2;6;-8}
x thuoc {0;2}
a) \(\left(3x-1\right)\left(2x+7\right)-\left(x+1\right)\left(6x-5\right)-\left(18x-12\right)\)
\(=6x^2+21x-2x-7-\left(6x^2-5x+6x-5\right)-18x+12\)\(=10\)
=>(2x-5)^x+2=(2x-5)^x+12
=>x+2=x+12
=>k co gia tri thoa man