a/ \(\dfrac{3-x}{12}=\dfrac{2x+2}{8}\)
\(< =>\dfrac{2\left(3-x\right)}{24}=\dfrac{3\left(2x+2\right)}{24}\)
\(< =>6-2x-6x-6=0\)
\(< =>-8x=0\)
\(< =>x=0\)
Vậy tập nghiệm.....
b/ \(\dfrac{x+3}{x-4}+\dfrac{x-3}{x+4}=\dfrac{2\left(x^2+12\right)}{x^2-16}\)
Tìm ĐKXĐ của pt là: \(x\ne\pm4\) (làm tắt, bạn làm rõ ra nhé)
\(\dfrac{x+3}{x-4}+\dfrac{x-3}{x+4}=\dfrac{2\left(x^2+12\right)}{x^2-16}\)
\(< =>\dfrac{\left(x+3\right)\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}+\dfrac{\left(x-3\right)\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{2\left(x^2+12\right)}{\left(x+4\right)\left(x-4\right)}\)
\(< =>x^2+3x+4x+12+x^2-3x-4x+12-2x^2-24=0\)
\(< =>0x=0\)
=> x có vô số nghiệm
Vậy ....
a) `(3-x)/12=(2x+2)/8`
`<=> (3-x)/12 =(x+1)/4`
`<=> 3-x=3(x+1)`
`<=>3-x=3x+3`
`<=> x=0`
Vậy `S={0}`.
b) ĐK: `x \ne \pm 4`
`(x+3)/(x-4)+(x-3)/(x+4)=(2(x^2+12))/(x^2-16)`
`<=> (x+3)(x+4)+(x-3)(x-4)=2(x^2+12)`
`<=> x^2+7x+12+x^2-7x+12=2x^2+24`
`<=> 0x=0`
Vậy PT có nghiệm với mọi x thỏa mãn điều kiện.
\(\dfrac{x+3}{x-4}+\dfrac{x-3}{x+4}=\dfrac{2\left(x^2+12\right)}{x^2-16}\)
⇔\(\dfrac{\left(x+3\right)\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}+\dfrac{\left(x-3\right)\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{2\left(x^2+12\right)}{\left(x-4\right)\left(x+4\right)}\)
⇔\(\dfrac{x^2+4x+3x+12}{\left(x-4\right)\left(x+4\right)}+\dfrac{x^2-4x-3x+12}{\left(x-4\right)\left(x+4\right)}=\dfrac{2x^2+24}{\left(x-4\right)\left(x+4\right)}\)
⇔\(\dfrac{x^2+7x+12}{\left(x-4\right)\left(x+4\right)}+\dfrac{x^2-7x+12}{\left(x-4\right)\left(x+4\right)}=\dfrac{2x^2+24}{\left(x-4\right)\left(x+4\right)}\)
⇒ \(x^2+7x+12+x^2-7x+12=2x^2+24\)
⇔ \(2x^2+24=2x^2+24\)
⇔ \(2x^2-2x^2=24-24\)
⇔ x=0
