Toán Lớp 8: thực hiện phép tính
a) 7x/2x(x+7)+3x+6/2x^2+14x
b)2x+1/2x^2-x+32x^2/1-4x^2+1-2x/2x^2+x
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Toán Lớp 8: thực hiện phép tính
a) 7x/2x(x+7)+3x+6/2x^2+14x
b)2x+1/2x^2-x+32x^2/1-4x^2+1-2x/2x^2+x
mik sẽ vote cho ai nhanh nhất
Comments ( 1 )
a)\dfrac{{7x}}{{2x\left( {x + 7} \right)}} + \dfrac{{3x + 6}}{{2{x^2} + 14x}}\\
= \dfrac{{7x}}{{2x\left( {x + 7} \right)}} + \dfrac{{3\left( {x + 2} \right)}}{{2x\left( {x + 7} \right)}}\\
= \dfrac{{7x + 3x + 6}}{{2x\left( {x + 7} \right)}}\\
= \dfrac{{10x + 6}}{{2x\left( {x + 7} \right)}}\\
b)\dfrac{{2x + 1}}{{2{x^2} – x}} + \dfrac{{32{x^2}}}{{1 – 4{x^2}}} + \dfrac{{1 – 2x}}{{2{x^2} + x}}\\
= \dfrac{{2x + 1}}{{x\left( {2x – 1} \right)}} + \dfrac{{32{x^2}}}{{\left( {1 – 2x} \right)\left( {2x + 1} \right)}} + \dfrac{{1 – 2x}}{{x\left( {2x + 1} \right)}}\\
= \dfrac{{ – \left( {2x + 1} \right)\left( {2x + 1} \right) + 32{x^3} + \left( {1 – 2x} \right)\left( {1 – 2x} \right)}}{{x\left( {1 – 2x} \right)\left( {1 + 2x} \right)}}\\
= \dfrac{{ – 4{x^2} – 4x – 1 + 32{x^3} + 1 – 4x + 4{x^2}}}{{x\left( {1 – 2x} \right)\left( {1 + 2x} \right)}}\\
= \dfrac{{32{x^3} – 8x}}{{x\left( {1 – 2x} \right)\left( {1 + 2x} \right)}}\\
= \dfrac{{ – 8x\left( {1 – 4{x^2}} \right)}}{{x\left( {1 – 4{x^2}} \right)}}\\
= – 8
\end{array}\]