2 câu trả lời
$ĐKXĐ:x \neq 0;-4;\dfrac{1}{2}$
$\dfrac{1-4x^2}{x^2+4x}:\dfrac{2-4x}{3x}$
$=\dfrac{(1-2x)(1+2x)}{x(x+4)}.\dfrac{3x}{2(1-2x)}$
$=\dfrac{1+2x}{x+4}.\dfrac{3}{2}$
$=\dfrac{3(1+2x)}{2(x+4)}$
$=\dfrac{3+6x}{2x+8}$
$\frac{1 - 4x^2}{x^2 + 4x}$ : $\frac{2 - 4x}{3x}$
$=^{}$ $\frac{( 1 - 4x^2 ) . 3x}{( x^2 + 4x ) ( 2 - 4x )}$
$=^{}$ $\frac{3x - 12x^3}{-4x^3 + 2x^2 + 8x - 16x^2}$
$=^{}$ $\frac{3x - 12x^3}{-4x^3 - 14x^2 + 8x}$
$=^{}$ $\frac{3 - 12x^2}{-4x^2 - 14x + 8}$
$\neq$ $TD^{}$
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