Question

Calculați :(2+4+...+200):[(4+8+...+100):13​

Answer 1

Răspuns:

(2+4+...+200):(4+8+...+100):13​=

Explicație pas cu pas:

2+4+...+200=

=2(1+2+3+...+100)

=2*100*(100+1):2

=100*101

=10100

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4+8+...+100=

=4(1+2+3+...+25)

=4*25*(25+1)/2

=2*25*26

=1300

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=> (2+4+...+200):(4+8+...+100):13​=10100:1300:13=$\frac{10100}{1300}:13=\frac{101}{13} *\frac{1}{13} =\frac{101}{169}$

Succes la scoala! :)