Toán Lớp 8: Thực hiện tính :X/x+3-1/3-x+5x-3/x2-9
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Toán Lớp 8: Thực hiện tính :X/x+3-1/3-x+5x-3/x2-9
Comments ( 2 )
x/(x+3) – 1/(3-x) + (5x-3)/(x^2-9)
= x/(x+3) + 1/(x-3) + (5x-3)/((x-3)(x+3))
= ( x (x-3) + (x+3) + (5x-3) )/((x-3)(x+3))
= (x^2 – 3x + x + 3 + 5x – 3)/((x-3)(x+3))
= (x^2 + 3x)/((x-3)(x+3))
= (x (x+3))/((x-3)(x+3))
= x/(x-3)
Giải đáp:
= x/{x – 3}
Lời giải và giải thích chi tiết:
x/{x + 3} – 1/{3 – x} + {5x – 3}/{x^2 – 9} (ĐKXĐ: x ne +- 3)
= x/{x + 3} – 1/{- (x – 3)} + {5x – 3}/{x^2 – 3^2}
= x/{x + 3} + 1/{x – 3} + {5x – 3}/{(x – 3)(x + 3)}
= {x(x – 3)}/{(x – 3)(x + 3)} + {x + 3}/{(x – 3)(x + 3)} + {5x – 3}/{(x – 3)(x + 3)}
= {x^2 – 3x}/{(x – 3)(x + 3)} + {x + 3}/{(x – 3)(x + 3)} + {5x – 3}/{(x – 3)(x + 3)}
= {x^2 – 3x + x + 3 + 5x – 3}/{(x – 3)(x + 3)}
= {x^2 + (5x – 3x + x) + (3 – 3)}/{(x – 3)(x + 3)}
= {x^2 + 3x}/{(x – 3)(x + 3)}
= {x(x + 3)}/{(x – 3)(x + 3)}
= x/{x – 3}
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