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a: \(=\dfrac{4}{5}+\dfrac{6}{5}\cdot\dfrac{15}{7}-\dfrac{3}{7}=\dfrac{4}{5}+\dfrac{90}{35}-\dfrac{3}{7}\)
\(=\dfrac{28}{35}+\dfrac{90}{35}-\dfrac{15}{35}=\dfrac{103}{35}\)
b: \(=\dfrac{9}{13}\left(\dfrac{5}{13}-\dfrac{6}{13}-\dfrac{20}{13}\right)=\dfrac{9}{13}\cdot\dfrac{-21}{13}=\dfrac{-189}{169}\)
f) \(2\cdot5^2+3:71^0-54:3^3\)
\(=2\cdot25+3:1-54:27\)
\(=50+3-2\)
\(=51\)
h) \(5\cdot3^2-32:4^2\)
\(=5\cdot9-32:16\)
\(=45-2\)
\(=43\)
k) \(5^6:5^4+2^3\cdot2^2-1^{2017}\)
\(=5^2+2^5-1\)
\(=25+32-1\)
\(=56\)
n) \(23\cdot75+5^2\cdot10+5^2\cdot13+180\)
\(=23\cdot25\cdot3+25\cdot10+25\cdot13+180\)
\(=25\cdot\left(23\cdot3+10+13\right)+180\)
\(=25\cdot92+180\)
\(=2300+180\)
\(=2480\)
f: =2*25+3-54:27
=50+3-2
=51
h: =5*9-32:16
=45-2=43
k: =5^2+2^5-1
=25+32-1
=25+31=56
n: =23*75+25*23+180
=2300+180
=2480
\(a,=-15x^3+10x^4+20x^2\\ b,=2x^3+2x^2+4x-x^2-x-2=2x^3+x^2+3x-2\)
3+5+7+...+77+79+100=
(3+5+7+...+77+79)+100=
{(3+79).[(79-3)/2+1]/2} + 100=
{82.[76/2+1]/2} + 100=
{82.[38+1]/2} + 100=
{82.39/2} + 100=
{82.19,5}+ 100=
{82.19,5}+ 100=
1599+100=
1699
a, - \(\dfrac{1}{3}\).\(xy\).(3\(x^3\).y2 - 6\(x^2\) + y2)
= - \(x^4\).y3 + 2\(x^3\).y - \(\dfrac{1}{3}\).\(xy^3\)
b, (2\(x\) -3).(4\(x\)2 + 6\(x\) + 9)
= (2\(x\))3 - 33
= 8\(x^3\) - 27
#)Giải :
\(\left(\frac{1}{2}\right)^{15}\div\left(\frac{1}{4}\right)^{20}=\left(\frac{1}{2}\right)^{15}\div\left(\frac{1}{2}\right)^{40}=\left(\frac{1}{2}\right)^{-25}\)