Làm bài 8 giúp mk vs, mk đang cần gấp ạ
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\(a,=\dfrac{4xy-1-2xy+1}{5x^2y}=\dfrac{6xy}{5x^2y}=\dfrac{6}{5x}\\ b,=\dfrac{x^2+8x-2x+8}{x\left(x-4\right)\left(x+4\right)}=\dfrac{\left(x+2\right)\left(x+4\right)}{x\left(x-4\right)\left(x+4\right)}=\dfrac{x+2}{x\left(x-4\right)}\\ c,=\dfrac{x^2+3x-x+1}{x\left(x+1\right)\left(x-1\right)}=\dfrac{\left(x+1\right)^2}{x\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{x\left(x-1\right)}\\ d,=\dfrac{x-3-x-3-2x}{\left(x-3\right)\left(x+3\right)}=\dfrac{-2\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{2}{3-x}\\ e,=\dfrac{x+1-1}{x+1}=\dfrac{x}{x+1}\\ f,=\dfrac{3x+5-5+9x}{6x^2y}=\dfrac{12x}{6xy}=\dfrac{2}{y}\)
\(g,=\dfrac{x^2+6x-2x+4}{x\left(x+2\right)\left(x-2\right)}=\dfrac{\left(x+2\right)^2}{x\left(x+2\right)\left(x-2\right)}=\dfrac{x+2}{x\left(x-2\right)}\\ h,=\dfrac{3x+1-3x+1+2x-3}{\left(3x-1\right)\left(3x+1\right)}=\dfrac{2x-1}{\left(3x-1\right)\left(3x+1\right)}\\ j,=\dfrac{5x+30+x^2-30}{x\left(x+6\right)}=\dfrac{x^2+5x}{x^2+6x}\\ k,=\dfrac{\left(x-7\right)\left(x+7\right)}{2x+1}\cdot\dfrac{-3}{x-7}=\dfrac{-3\left(x+7\right)}{2x+1}\\ l,=\dfrac{x\left(3x-2\right)}{x^2-1}\cdot\dfrac{\left(x^2+1\right)\left(x^2-1\right)}{\left(3x-2\right)^3}=\dfrac{x\left(x^2+1\right)}{\left(3x-2\right)^2}\)
sin 650=cos 350
\(cos70^0=sin30^0\)
\(tan80^0=cot20^0\)
\(cot68^0=tan32^0\)
a: Xét ΔADM và ΔCBN có
AD=CB
\(\widehat{DAM}=\widehat{BCN}\)
AM=CN
Do đó: ΔADM=ΔCBN
Suy ra: DM=BN