Operazioni con frazioni

2 + 1/4 - 2/5 + 3/20=

=(2·20 + 1·5 - 2·4 + 3)/20=

=(40 + 5 - 8 + 3)/20=

=40/20=2

(40+5-8+3)/20 = 40/20 = 2 

97/2)

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$\small 2+\dfrac{1}{4}-\dfrac{2}{5}+\dfrac{3}{20}=$

minimo comune multiplo dei denominatori = 20, quindi moltiplica tutto per 20:

$\small = \dfrac{40+5-8+3}{20}=$

$\small = \dfrac{\cancel{40}^2}{\cancel{20}_1}= 2$

(11+4-10)/12 = 5/12

(15+8-2)/12 = 21/12

(6-5+3)/10 = 2/5

(54-45+10)/30 = 19/30

(12-9+6)/24 = 9/24 = 3/8

(20+6-8)/15 = 18/15 = 6/5 

(30-2+35)/21 = 63/21 = 3

(24-9+12)/24 = 27/24 = 9/8

(9+10-12)/30 = 7/30

(20+1-7)/14 = 14/14 = 1

(35+40-15)/30 = 60/30 = 2

(4-1+27)/18 = 30/18 = 5/3

(17-15+20)/12 = 11/6 

(25-12-10)/20 = 3/20

(28-15-1)/10 = 12/10 = 6/5

(18+15-32)/24 = 1/24

(42-25+10)/30 = 27/30 = 9/10