Tìm nghiệm của phương trình:
\(\frac{148-x}{13}+\frac{169-x}{17}+\frac{186-x}{17}+\frac{199-x}{16}=10\)
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\(\frac{148-x}{13}-1+\frac{169-x}{17}-2+\frac{186-x}{17}-3+\frac{199-x}{16}-4=0\)\(\frac{135-x}{13}+\frac{135-x}{17}+\frac{135-x}{17}+\frac{135-x}{16}=0\)
(135-x)(\(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\))=0
135-x=0
x=135
Có : \(\frac{148-x}{13}+\frac{169-x}{17}+\frac{186-x}{17}+\frac{199-x}{16}=10\)
\(\Leftrightarrow\)\(\left(\frac{148-x}{13}-1\right)+\)\(\left(\frac{169-x}{17}-2\right)+\)\(\left(\frac{186-x}{17}-3\right)\) + \(\left(\frac{199-x}{16}-4\right)=10\)
\(\Leftrightarrow\) \(\frac{135-x}{13}+\frac{135-x}{17}+\frac{135-x}{17}+\frac{135-x}{16}\)= 10
\(\Leftrightarrow\) \(\left(135-x\right)\left(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\right)=0\)
\(\Leftrightarrow\) \(135-x=0\) \(\left(\frac{1}{13}+\frac{1}{17}+\frac{1}{17}+\frac{1}{16}\right)\ne0\)
\(\Leftrightarrow\) \(x=135\)
Vậy \(x=135\)
cộng thêm 1 vào mỗi vế là ra ấy mà. bạn động não chút đi
\(\Leftrightarrow\frac{148-x}{25}-1+\frac{169-x}{23}-2+\frac{186-x}{21}-3+\frac{199-x}{19}-4=0\)
\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)
\(\Leftrightarrow\left(123-x\right)\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)
Mà \(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\ne0\)
\(\Rightarrow123-x=0\Rightarrow x=123\)
Vậy Tập nghiệm của phương trình là \(S=\left\{123\right\}\)
<=> 148-×/25 -1 + 169-x/23 -2 + 186-x/21 - 3 + 199-×/19 - 4=0
<=> (123-x)(1/25+1/23+1/21+1/19)=0
<=> x=123
Chúc bạn học tốt
\(\frac{148-x}{25}+\frac{169-x}{23}+\frac{186-x}{21}+\frac{199-x}{19}=10\)
\(\Leftrightarrow\frac{148-x}{25}-1+\frac{169-x}{23}-2+\frac{186-x}{21}-3+\frac{199-x}{19}-4=0\)
\(\Leftrightarrow\frac{148-x}{25}-\frac{25}{25}+\frac{169-x}{23}-\frac{46}{23}+\frac{186-x}{21}-\frac{63}{21}+\frac{199-x}{19}-\frac{76}{19}=0\)
\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)
\(\Leftrightarrow\left(123-x\right).\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)
\(\Leftrightarrow123-x=0\left(\text{vì }\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\ne0\right)\)
<=>x=123
Vậy S={123}
a) \(\frac{148-x}{25}+\frac{169-x}{23}+\frac{186-x}{21}+\frac{199-x}{19}=10\)
\(\Leftrightarrow\left(\frac{148-x}{25}-1\right)+\left(\frac{169-x}{23}-2\right)+\left(\frac{186-x}{21}-3\right)+\left(\frac{199-x}{19}-4\right)=0\)
\(\Leftrightarrow\frac{123-x}{25}+\frac{123-x}{23}+\frac{123-x}{21}+\frac{123-x}{19}=0\)
\(\Leftrightarrow\left(123-x\right)\left(\frac{1}{25}+\frac{1}{23}+\frac{1}{21}+\frac{1}{19}\right)=0\)
\(\Leftrightarrow x=123\)
c) \(x^4-10.2^x+16=0\)
\(\Leftrightarrow\left(2^x\right)^2-10.2^x+16=0\)
Ta có:
\(2^x=t\)
\(\Rightarrow t^2-10t+16=0\)
\(\Leftrightarrow\orbr{\begin{cases}t=8\\t=2\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)
\(\left(\frac{148-x}{13}-1\right)+\left(\frac{169-x}{17}-2\right)+\left(\frac{186-x}{17}-3\right)+\left(\frac{199-x}{16}-4\right)=10-1-2-3-4\)
VT có tử =(135-x) VP=0
Vậy: x=135