Toán Lớp 8: Rút gọn:
(2/(1+2x) + (4x^2 + 1)/(4x^2 – 1) – 1/(1-2x)):2/(4x^2 -1)
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Toán Lớp 8: Rút gọn:
(2/(1+2x) + (4x^2 + 1)/(4x^2 – 1) – 1/(1-2x)):2/(4x^2 -1)
Comments ( 2 )
(\frac{2}{1+2x}+\frac{4x^2+1}{4x^2-1}-\frac{1}{1-2x}):\frac{2}{4x^2-1} ĐK:x \ne \frac{+-1}{2}
=(\frac{2}{2x+1}+\frac{4x^2+1}{(2x-1)(2x+1)}+\frac{1}{2x-1}):\frac{2}{4x^2-1}
=\frac{2(2x-1)+4x^2+1+2x+1}{(2x-1)(2x+1)}.\frac{4x^2-1}{2}
=\frac{4x-2+4x^2+1+2x+1}{4x^2-1}.\frac{4x^2-1}{2}
=\frac{4x^2+6x}{2}
=\frac{2(2x^2+3x)}{2}
=2x^2+3x
(2/(1+2x) + (4x^2 + 1)/(4x^2 – 1) – 1/(1-2x)):2/(4x^2 -1)
=[2/(2x+1) + (4x^2 + 1)/((2x-1)(2x+1)) + 1/(2x-1)].(4x^2 -1)/2
=(2(2x-1)+4x^2+1+(2x+1))/((2x-1)(2x+1)).((2x-1)(2x+1))/2
=(4x-2+4x^2+1+2x+1)/((2x-1)(2x+1)).((2x-1)(2x+1))/2
=(4x^2+6x)/2
=(2x(2x+3))/2
=x(2x+3)