Xác định các số a, b biết:
\(\frac{\left(3x+1\right)}{\left(x+1\right)^3}\)=\(\frac{a}{\left(x+1\right)^3}\)+\(\frac{b}{\left(x+1\right)^2}\)
\(\text{xác định các số a,b biết :}\)
\(\frac{3x+1}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b}{\left(x+1\right)^2}\)
Ta có:\(\frac{a}{\left(x+1\right)^3}+\frac{b}{\left(x+1\right)^2}=\frac{a+bx+b}{\left(x+1\right)^3}\)
Vì \(\frac{a+bx+b}{\left(x+1\right)^3}\) và \(\frac{3x+1}{\left(x+1\right)^3}\) đều có chung tử
Suy ra a+bx+b=3x+1
3, Xác định các số a, b để \(\frac{\left(3x+1\right)}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b}{\left(x+1\right)^2}\)
\(\frac{3x+1}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b.\left(x+1\right)}{\left(x+1\right)^3}=\frac{bx+a+b}{\left(x+1\right)^3}\)
=>b = 3
=> a+b =1=> a= 1-b=1-3=-2
Vậy a = -2 ; b = 3
Xác định các số a,b biết: \(\frac{3x+1}{\left(x+1\right)^3}\)= \(\frac{a}{\left(x+1\right)^3}\)+ \(\frac{b}{\left(x+1\right)^2}\)
Ta có:
\(\frac{3x+1}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b}{\left(x+1\right)^2}=\frac{bx+b+a}{\left(x+1\right)^3}\)
Đồng nhất thức 2 vế được: \(\hept{\begin{cases}b=3\\a+b=1\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}a=-2\\b=3\end{cases}}\)
Xác định các số a, b, c biết
\(\frac{1}{\left(x+1\right)^2\left(x+2\right)}=\frac{a}{x+1}+\frac{b}{\left(x+1\right)^2}+\frac{c}{x+2}\)
Xác định các số a,b biết: \(\frac{3x+1}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b}{\left(x+1\right)^2}\)
Giúp hộ!!!
\(\frac{3x+1}{\left(x+1\right)^3}=\frac{a}{\left(x+1\right)^3}+\frac{b\left(x+1\right)}{\left(x+1\right)^3}\)
\(\Leftrightarrow\frac{3x+1}{\left(x+1\right)^3}=\frac{bx+a+b}{\left(x+1\right)^3}\)
Đồng nhất 2 vế ta được: \(\left\{{}\begin{matrix}b=3\\a+b=1\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}a=-2\\b=3\end{matrix}\right.\)
xác định a,b,c biệt :
a/ \(\frac{9x^2-16x+4}{x^3-3x^2+2x}=\frac{a}{x}+\frac{b}{x-1}+\frac{c}{x-2}\)
b/ \(\frac{1}{\left(x-1\right)^2\left(x-2\right)}=\frac{a}{x-1}+\frac{b}{\left(x-1\right)^2}+\frac{c}{x-2}\)
bài 2
a 0,75x (x +5 )= x+5 (3- 1,25x)
b\(\frac{4}{5}x-3=\frac{1}{5}x\left(4x-15\right)\)
c(x-3) -\(\frac{\left(x-3\right)\left(2x-5\right)}{6}=\frac{\left(x-3\right)\left(3-x\right)}{4}\)
d \(\frac{\left(3x+1\right)\left(3x-2\right)}{3}+5\left(3x+1\right)=\frac{2\left(2x+1\right)\left(3x+1\right)}{3}+2x\left(3x+1\right)\)
Xác định các số hữu tỉ a , b , c sao cho :
\(\frac{1}{\left(x+1\right)^2\left(x+2\right)}=\frac{a}{x+1}+\frac{b}{\left(x+1\right)^2}+\frac{c}{x+2}\)
Tìm x, biết:
a) \(4\left|3x-1\right|+\left|x\right|-2\left|x-5\right|+7\left|x-3\right|=12\)
b) \(2\left|x+3\frac{1}{2}\right|+\left|x\right|-3\frac{1}{2}=\left|2\frac{1}{5}-x\right|\)