Ta có : \(\frac{4x+7}{3}=\frac{12}{4x+7}\)
\(\Rightarrow\left(4x+7\right)^2=12.3=36\)
\(\Rightarrow4x+7=\orbr{\begin{cases}-6\\6\end{cases}}\)
\(\Rightarrow4x=\orbr{\begin{cases}-13\\-1\end{cases}}\)
\(\Rightarrow x=\orbr{\begin{cases}\frac{-13}{4}\\\frac{-1}{4}\end{cases}}\)
Tìm x:\(a,\frac{6x-5}{-7}=\frac{5x-3}{-5}\\ b,\frac{12-7x}{-13}=\frac{4-3x}{-5}\\ c,\frac{2x+4}{7}=\frac{4x-2}{15}\)
Tìm GTNN
A=\(\frac{21|4x+6|+33}{3|4x+6|+5}\)
B=\(\frac{6|y+5|+14}{2|+5|+14}\)
C=\(\frac{-15|x+7|-68}{3|x+7|+12}\)
\(\frac{x-1}{12}+\frac{2x-3}{23}+\frac{3x-5}{34}+\frac{4x-7}{45}-4\)
Tìm x biết
a,\(\left(\frac{4}{5}\right)^{2x+7}\text{=}\frac{625}{256}\)
b,\(\frac{7^{x+2}+7^{x+1}+7^x}{57}\text{=}\frac{5^{2x}+5^{2x+1}+5^{2x+3}}{131}\)
c,\(\left(4x-3\right)^4\text{=}\left(4x-3\right)^2\)
d,\(\frac{2x+3}{5x+2}\text{=}\frac{4x+5}{10x+2}\)
e,\(\frac{3x-1}{40-5x}\text{=}\frac{2x-3x}{5x-34}\)
f,\(\frac{15}{x-9}\text{=}\frac{20}{y-12}\text{=}\frac{40}{z-2x}\) và \(xy\text{=}1200\)
Tìm x biết:
\(\left|x+\frac{2}{7}\right|+\left|x+\frac{4}{7}\right|+\left|x+3\frac{1}{7}\right|=4x\)
Tìm x:
\(2x-3=x+\frac{1}{2}\)
\(4x-\left(2x+1\right)=3-\frac{1}{3}+x\)
\(2x-\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-...-\frac{1}{49\cdot50}=7-\frac{1}{50}+x\)
Tìm x, biết :
\(a.\frac{7^{x+2}+7^{x+1}+7x}{57}=\frac{5^{2x}+5^{2x+1}+5^{2x+3}}{131}\)
\(b.\left(4x-3\right)^4=\left(4x-3\right)^2\)
Tìm x, biết:\(\frac{5x-1}{3}=\frac{7y-6}{5}=\frac{5x-7y-7}{4x}\)
tìm x;y\(\left(x-7\right)^{x+1}-\left(x-7\right)^{x+1}\)=0
\(\frac{5x-1}{3}=\frac{7y-6}{5}=\frac{6x+7y-7}{4x}\)
