Toán làm tính cộng : (2/x-2)+(2/x+2)+(3x+2/4-x^2) 18/07/2021 By Katherine làm tính cộng : (2/x-2)+(2/x+2)+(3x+2/4-x^2)
ĐKXĐ: \(x\ne ±2\) \(\dfrac{2}{x-2}+\dfrac{2}{x+2}+\dfrac{3x+2}{4-x^2}\\=\dfrac{2(x+2)}{(x+2)(x-2)}+\dfrac{2(x-2)}{(x+2)(x-2)}-\dfrac{3x+2}{x^2-4}\\=\dfrac{2x+4}{(x+2)(x-2)}+\dfrac{2x-4}{(x+2)(x-2)}-\dfrac{3x+2}{(x-2)(x+2)}\\=\dfrac{2x+4+2x-4-3x-2}{(x-2)(x+2)}\\=\dfrac{x-2}{(x-2)(x+2)}\\=\dfrac{1}{x+2}\) Trả lời
Đáp án: `1/(x+2)` Giải thích các bước giải: `2/(x-2)+2/(x+2)+(3x+2)/(4-x²)“(ĐKXĐ:“x`$\neq$ `±2)` `=2/(x-2)+2/(x+2)+(-3x-2)/(x²-4)` `=[2(x+2)]/(x²-4)+[2(x-2)]/(x²-4)+(-3x-2)/(x²-4)` `=[2(x+2)+2(x-2)-3x-2]/(x²-4)` `=[2x+4+2x-4-3x-2]/(x²-4)` `=(x-2)/(x²-4)``=(x-2)/[(x+2)(x-2)]``=1/(x+2)` Trả lời
ĐKXĐ: \(x\ne ±2\)
\(\dfrac{2}{x-2}+\dfrac{2}{x+2}+\dfrac{3x+2}{4-x^2}\\=\dfrac{2(x+2)}{(x+2)(x-2)}+\dfrac{2(x-2)}{(x+2)(x-2)}-\dfrac{3x+2}{x^2-4}\\=\dfrac{2x+4}{(x+2)(x-2)}+\dfrac{2x-4}{(x+2)(x-2)}-\dfrac{3x+2}{(x-2)(x+2)}\\=\dfrac{2x+4+2x-4-3x-2}{(x-2)(x+2)}\\=\dfrac{x-2}{(x-2)(x+2)}\\=\dfrac{1}{x+2}\)
Đáp án:
`1/(x+2)`
Giải thích các bước giải:
`2/(x-2)+2/(x+2)+(3x+2)/(4-x²)“(ĐKXĐ:“x`$\neq$ `±2)`
`=2/(x-2)+2/(x+2)+(-3x-2)/(x²-4)`
`=[2(x+2)]/(x²-4)+[2(x-2)]/(x²-4)+(-3x-2)/(x²-4)`
`=[2(x+2)+2(x-2)-3x-2]/(x²-4)`
`=[2x+4+2x-4-3x-2]/(x²-4)`
`=(x-2)/(x²-4)`
`=(x-2)/[(x+2)(x-2)]`
`=1/(x+2)`