\(\Leftrightarrow2.5:x=2+\dfrac{2}{3}-2-\dfrac{1}{5}=\dfrac{7}{15}\)

hay \(x=\dfrac{5}{2}:\dfrac{7}{15}=\dfrac{5}{2}\cdot\dfrac{15}{7}=\dfrac{75}{14}\)

= 3/4 + 1/3 = 13/12

5/4 x X = 5/8

X = 5/8 : 5/4

X = 1/2

vậy X = ...

\(\dfrac{3}{5}:\dfrac{4}{5}+\dfrac{1}{2}\times\dfrac{2}{3}=\dfrac{3}{4}+\dfrac{1}{3}+\dfrac{9}{12}+\dfrac{4}{12}=\dfrac{11}{12}\)

\(\dfrac{5}{4}\times x=\dfrac{5}{8}\)

\(x=\dfrac{5}{8}:\dfrac{5}{4}\)

\(x=\dfrac{1}{2}\)

Tính giá trị biểu thức
   \(\dfrac{3}{5}:\dfrac{4}{5}+\dfrac{1}{2}x\dfrac{2}{3}=\dfrac{3}{5}x\dfrac{5}{4}+\dfrac{1}{3}=\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{9+4}{12}=\dfrac{13}{12}\)  

Tìm x
    \(\dfrac{5}{4}\)xX=\(\dfrac{3}{8}+\dfrac{1}{4}\)
    \(\dfrac{5}{4}\)xX=\(\dfrac{5}{8}\)
    x=\(\dfrac{5}{8}\) :\(\dfrac{5}{4}\)
    x=\(\dfrac{1}{2}\)

a)\(f\left(1\right)=2.1^2+5.1-3=2+5-3=4\)

\(f\left(0\right)=0+0-3=-3\)

\(f\left(1,5\right)=2.\left(1,5\right)^2-5.1,5-3=4,5-7,5-3=-6\)

b)\(f\left(3\right)=3a-3=9=>>3a=12=>a=4\)

\(f\left(5\right)=5a-3=11=>5a=14=>a=\dfrac{14}{5}\)

\(f\left(-1\right)=-a-3=6=>-a=9=>a=-9\)

\(\dfrac{9}{7}x+\dfrac{5}{7}x=\dfrac{2}{3}\)

\(\Leftrightarrow x\left(\dfrac{9}{7}+\dfrac{5}{7}\right)=\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{14}{7}x=\dfrac{2}{3}\)

\(\Leftrightarrow2x=\dfrac{2}{3}\)

\(\Leftrightarrow x=\dfrac{2}{3}:2\)

\(\Leftrightarrow x=\dfrac{2}{3}\times\dfrac{1}{2}\)

\(\Leftrightarrow x=\dfrac{2}{6}\)

\(\Leftrightarrow x=\dfrac{1}{3}\)

\(\left|x-1\right|=x+3\left(ĐK:x\ge-3\right)\\ \Leftrightarrow\left[{}\begin{matrix}x-1=x+3\\x-1=-x-3\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x-x=1+3\\x+x=1-3\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}0x=4\\2x=-2\end{matrix}\right.\\ \Leftrightarrow x=-1\left(tmđk\right)\)

Vậy x = -1 là nghiệm của pt.

Ta có : \(\dfrac{x}{2}=\dfrac{1-x}{3}\)

\(\Leftrightarrow3x=2\left(1-x\right)\)

\(\Leftrightarrow3x=2-2x\)

\(\Leftrightarrow5x=2\)

\(\Leftrightarrow x=\dfrac{5}{2}\)

Vậy ...

Ta có: \(\dfrac{x}{2}=\dfrac{1-x}{3}\)

\(\Leftrightarrow3x=2\left(1-x\right)\)

\(\Leftrightarrow3x=2-2x\)

\(\Leftrightarrow3x+2x=2\)

\(\Leftrightarrow5x=2\)

hay \(x=\dfrac{2}{5}\)

Vậy: \(x=\dfrac{2}{5}\)

A(x)=-2 rồi thì A(x):B(x) dư 6 sao được bạn? Bạn xem lại đề.

\(f\left(3\right)=3a-3=9\)

\(3a=12\Rightarrow a=4\)

\(f\left(5\right)=5a-3=11\)

\(5a=14\Rightarrow a=\dfrac{14}{5}\)

\(f\left(-1\right)=-a-3=6\)

\(-a=9\Rightarrow a=9\)

a) \(f\left(x\right)=2x^2+5x-3\)

\(f\left(1\right)=2.1^2+5.1-3=2+5-3=4\)

\(f\left(0\right)=-3\)

\(f\left(1,5\right)=2.\left(1,5\right)^2+5.1,5-3=2.2,25+7,5-3=9\)