Toán Lớp 8: 3 $\frac{3}{2x+6}$- $\frac{x-6}{2x^2+6x}$
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Toán Lớp 8: 3 $\frac{3}{2x+6}$- $\frac{x-6}{2x^2+6x}$
Comments ( 2 )
3, \frac{3}{2x+6}-\frac{x-6}{2x^2+6x} (ĐK:x \ne 0,x \ne -3)
=\frac{3}{2x+6}-\frac{x-6}{x(2x+6)}
=\frac{3x}{x(2x+6)}-\frac{x-6}{x(2x+6)}
=\frac{3x-x+6}{x(2x+6)}
=\frac{2x+6}{x(2x+6)}
=\frac{1}{x}
Giải đáp:
= {1}/x
Lời giải và giải thích chi tiết:
3)
3/{2x + 6} – {x – 6}/{2x^2 + 6x} (ĐKXĐ: x ne 0 ; x ne – 3)
= 3/{2x + 6} – {x – 6}/{x . 2x + x . 6}
= 3/{2x + 6} – {x – 6}/{x(2x + 6)}
= {3x}/{x(2x + 6)} – {x – 6}/{x(2x + 6)}
= {3x – (x – 6)}/{x(2x + 6)}
= {3x – x + 6}/{x(2x + 6)}
= {2x + 6}/{x(2x + 6)}
= {2 . x + 2 . 3}/{x(2 . x + 2 . 3)}
= {2(x + 3)}/{2x(x + 3)}
= {1}/x
#SunHee