Đáp án: $\text{ 7² -3(x-5)² =1}$ $\text{<=> 49 -3(x²-10x+25)=1 }$ $\text{<=>49 – 3x²+30x -75=1 }$ $\text{<=>-3x²+30x -75-1+49 =0 }$ $\text{<=>-3x²+30x -27=0 }$ $\text{<=> -3x²+3x +27x-27=0 }$ $\text{<=>-3x(x-1) +27(x-1)=0 }$ $\text{<=>(x-1)(-3x+27)=0}$ $\text{<=>\(\left[ \begin{array}{l}x-1=0\\-3x+27=0\end{array} \right.\) }$ $\text{<=>\(\left[ \begin{array}{l}x=1\\-3x=-27 <=> x= -27 : (-3) =9\end{array} \right.\) }$ $\text{Vậy x={1 ;9} }$ Trả lời
`7^2-3(x-5)^2=1` `⇒49-3(x-5)^2=1` `⇒3(x-5)^2=48` `⇒(x-5)^2=16` `⇒(x-5)^2=(±4)^2` `⇒x-5=±4` \(⇒\left[ \begin{array}{l}x-5=4⇒x=9\\x-5=-4⇒x=1\end{array} \right.\) `Vậy` `x∈{1;9}` Trả lời
Đáp án:
$\text{ 7² -3(x-5)² =1}$
$\text{<=> 49 -3(x²-10x+25)=1 }$
$\text{<=>49 – 3x²+30x -75=1 }$
$\text{<=>-3x²+30x -75-1+49 =0 }$
$\text{<=>-3x²+30x -27=0 }$
$\text{<=> -3x²+3x +27x-27=0 }$
$\text{<=>-3x(x-1) +27(x-1)=0 }$
$\text{<=>(x-1)(-3x+27)=0}$
$\text{<=>\(\left[ \begin{array}{l}x-1=0\\-3x+27=0\end{array} \right.\) }$
$\text{<=>\(\left[ \begin{array}{l}x=1\\-3x=-27 <=> x= -27 : (-3) =9\end{array} \right.\) }$
$\text{Vậy x={1 ;9} }$
`7^2-3(x-5)^2=1`
`⇒49-3(x-5)^2=1`
`⇒3(x-5)^2=48`
`⇒(x-5)^2=16`
`⇒(x-5)^2=(±4)^2`
`⇒x-5=±4`
\(⇒\left[ \begin{array}{l}x-5=4⇒x=9\\x-5=-4⇒x=1\end{array} \right.\)
`Vậy` `x∈{1;9}`