X = \(\dfrac{4}{7}:\dfrac{3}{5}=\dfrac{20}{21}\)

Học tốt

X = 

Bài 1: 

a) Ta có: \(\dfrac{17}{6}-x\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)

\(\Leftrightarrow\dfrac{17}{6}-x^2+\dfrac{7}{6}x-\dfrac{7}{4}=0\)

\(\Leftrightarrow-x^2+\dfrac{7}{6}x+\dfrac{13}{12}=0\)

\(\Leftrightarrow-12x^2+14x+13=0\)

\(\Delta=14^2-4\cdot\left(-12\right)\cdot13=196+624=820\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{14-2\sqrt{205}}{-24}=\dfrac{-7+\sqrt{205}}{12}\\x_2=\dfrac{14+2\sqrt{2015}}{-24}=\dfrac{-7-\sqrt{205}}{12}\end{matrix}\right.\)

b) Ta có: \(\dfrac{3}{35}-\left(\dfrac{3}{5}-x\right)=\dfrac{2}{7}\)

\(\Leftrightarrow\dfrac{3}{5}-x=\dfrac{3}{35}-\dfrac{10}{35}=\dfrac{-7}{35}=\dfrac{-1}{5}\)

hay \(x=\dfrac{3}{5}-\dfrac{-1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)

ai giúp mik vs

Bài 3: 

a) Ta có: \(2x-3=x+\dfrac{1}{2}\)

\(\Leftrightarrow2x-x=\dfrac{1}{2}+3\)

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

b) Ta có: \(4x-\left(x+\dfrac{1}{2}\right)=2x-\left(\dfrac{1}{2}-5\right)\)

\(\Leftrightarrow3x-\dfrac{1}{2}-2x+\dfrac{1}{2}-5=0\)

\(\Leftrightarrow x=5\)

\(9\times x+1,85\times x=48\\ \left(9+1,85\right)\times x=48\\ 10,85\times x=48\\ x=48:10,85\\ x=\dfrac{960}{217}\)

Đề có cho đa thức P(x) không bạn?

Vì P(x) chia cho đa thức bậc 2 nên dư là đa thức bậc 1

Gọi đa thức ấy là \(ax+b\)

\(\Leftrightarrow P\left(x\right)=\left(x^2-4x+3\right)\cdot a\left(x\right)+ax+b\\ \Leftrightarrow P\left(x\right)=\left(x-1\right)\left(x-3\right)\cdot a\left(x\right)+ax+b\)

\(P\left(1\right)=3\Leftrightarrow a+b=3\\ P\left(3\right)=7\Leftrightarrow3a+b=7\)

Từ đó ta có hệ \(\left\{{}\begin{matrix}a+b=3\\3a+b=7\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2a=4\\a+b=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=2\\b=1\end{matrix}\right.\)

Vậy đa thức dư là \(2x+1\)

8 , 15 x X + 1 , 85 x X = 124 

( 8 , 15 + 1 , 85 ) x X  = 124 

10 x X                       = 124 

       X                       = 124 : 10 

       X                       = 12 , 4 

 Vậy X = 12 , 4 

Tham khảo nha !!! 

8 , 15 x X + 1 , 85 x X = 124 

( 8 , 15 + 1 , 85 ) x X  = 124 

10 x X                       = 124 

       X                       = 124 : 10 

       X                       = 12 , 4 

 Vậy X = 12 , 4 

Tham khảo nha !!! 

@_@

\(8,15\times x+1,85\times x=124\)

\(x\times\left(8,15+1,85\right)=124\)

\(x\times10=124\)

\(x=124:10\)

\(x=12,4\)

=>2/3:x=-7-1/3=-22/3

=>x=-2/3:22/3=-2/3*3/22=-1/11

\(\dfrac{1}{3}\)+\(\dfrac{2}{3}\):x=-7

     \(\dfrac{2}{3}\):x=(-7)-\(\dfrac{1}{3}\)

     \(\dfrac{2}{3}\):x=\(\dfrac{-22}{3}\)

         x=\(\dfrac{2}{3}\):\(\dfrac{-22}{3}\)

         x=\(\dfrac{-1}{11}\) 

vậy x=\(\dfrac{-1}{11}\)

\(\dfrac{1}{3}+\dfrac{2}{3}:x=-7\\ \Rightarrow\dfrac{2}{3}:x=-7-\dfrac{1}{3}\\ \Rightarrow\dfrac{2}{3}:x=-\dfrac{21}{3}-\dfrac{1}{3}\\ \Rightarrow\dfrac{2}{3}:x=\dfrac{-22}{3}\\ \Rightarrow x=\dfrac{2}{3}:-\dfrac{22}{3}\\ \Rightarrow x=\dfrac{2}{3}\times-\dfrac{3}{22}\\ \Rightarrow x=-\dfrac{1}{11}\)

Ta có:

D(x) = \(\left(5x^3-6x\right)-\left(6x-5x^3+7\right)\)

D(x) = \(5x^3-6x-6x+5x^3-7\)

D(x) = \(10x^3-12x-7\)