Toán Giải PT: $\frac{25}{9 + x}$ + $\frac{16}{9 – x}$ = $\frac{9}{2}$ 09/09/2021 By Ivy Giải PT: $\frac{25}{9 + x}$ + $\frac{16}{9 – x}$ = $\frac{9}{2}$
Đáp án: \(\rm S=\left\{{1}\right\}\) Giải thích các bước giải: \(\dfrac{25}{9+x}+\dfrac{16}{9-x}=\dfrac{9}{2}\,\,\,\,\,\,ĐKXĐ:\begin{cases}x\neq9\\x\neq-9\end{cases}\\\Leftrightarrow\dfrac{50(9-x)}{2(9+x)(9-x)}+\dfrac{32(9+x)}{2(9+x)(9-x)}=\dfrac{9(9+x)(9-x)}{2(9+x)(9-x)}\\\Rightarrow50(9-x)+32(9+x)=9(9+x)(9-x)\\\Leftrightarrow450-50x+288+32x=9(81-x^2)\\\Leftrightarrow-18x+728=729-9x^2\\\Leftrightarrow9x^2-18x+738-729=0\\\Leftrightarrow9x^2-18x+9=0\\\Leftrightarrow9(x^2-2x+1)=0\\\Leftrightarrow9(x-1)^2=0\\\Leftrightarrow x-1=0\\\Leftrightarrow x = 1\,\rm(tmđk)\\Vậy\ S=\left\{{1}\right\}\) Trả lời
Đáp án + Giải thích các bước giải: `frac{25}{9+x}+frac{16}{9-x}=9/2` Điều kiện: `x\ne±9` `<=>frac{25}{9+x}+frac{16}{9-x}-9/2=0` `<=>frac{50(9-x)+32(9+x)-9(9+x)(9-x)}{2(9+x)(9-x)}=0` `=>50(9-x)+32(9+x)-9(9+x)(9-x)=0` `<=>450-50x+288+32x-9(81-x^2)=0` `<=>450-50x+288+32x-729+9x^2=0` `<=>9x^2-18x+9=0` `<=>9(x^2-2x+1)=0` `<=>x^2-2x+1=0` `<=>(x-1)^2=0` `<=>x-1=0` `<=>x=1` `text{( Thoả mãn điều kiện )}` Vậy `S={1}` Trả lời
Đáp án:
\(\rm S=\left\{{1}\right\}\)
Giải thích các bước giải:
\(\dfrac{25}{9+x}+\dfrac{16}{9-x}=\dfrac{9}{2}\,\,\,\,\,\,ĐKXĐ:\begin{cases}x\neq9\\x\neq-9\end{cases}\\\Leftrightarrow\dfrac{50(9-x)}{2(9+x)(9-x)}+\dfrac{32(9+x)}{2(9+x)(9-x)}=\dfrac{9(9+x)(9-x)}{2(9+x)(9-x)}\\\Rightarrow50(9-x)+32(9+x)=9(9+x)(9-x)\\\Leftrightarrow450-50x+288+32x=9(81-x^2)\\\Leftrightarrow-18x+728=729-9x^2\\\Leftrightarrow9x^2-18x+738-729=0\\\Leftrightarrow9x^2-18x+9=0\\\Leftrightarrow9(x^2-2x+1)=0\\\Leftrightarrow9(x-1)^2=0\\\Leftrightarrow x-1=0\\\Leftrightarrow x = 1\,\rm(tmđk)\\Vậy\ S=\left\{{1}\right\}\)
Đáp án + Giải thích các bước giải:
`frac{25}{9+x}+frac{16}{9-x}=9/2` Điều kiện: `x\ne±9`
`<=>frac{25}{9+x}+frac{16}{9-x}-9/2=0`
`<=>frac{50(9-x)+32(9+x)-9(9+x)(9-x)}{2(9+x)(9-x)}=0`
`=>50(9-x)+32(9+x)-9(9+x)(9-x)=0`
`<=>450-50x+288+32x-9(81-x^2)=0`
`<=>450-50x+288+32x-729+9x^2=0`
`<=>9x^2-18x+9=0`
`<=>9(x^2-2x+1)=0`
`<=>x^2-2x+1=0`
`<=>(x-1)^2=0`
`<=>x-1=0`
`<=>x=1` `text{( Thoả mãn điều kiện )}`
Vậy `S={1}`