Espressioni con frazioni

157) che problemi hai a risolvere le espressioni? Non sai trovare il mcm?

mcm (2; 6; 4) = 12;

mcm (6; 15; 30) = 30;     mcm(2; 4) = 4.

7/2 + 1 + [1/8 + (6/12 + 22/12 - 9/12) - (25/30 + 16/30 - 1/30)] + 1/8 - (6/4 + 1/4) =

= 7/2 + 1 + [1/8 + 19/12 - 40/30 ] + 1/8 - 7/4 =

40/30 = 4/3;    mcm(8; 12; 3) = 3 * 8 = 24;

= 7/2 + 1 + [1/8 + 19/12 - 4/3 ] + 1/8 - 7/4 =

= 7/2 + 1 + [3/24 + 38/24 - 32/24] + 1/8 - 7/4 =

= 7/2 + 1 + 9/24 + 1/8 - 7/4 = 

9/24 = 3/8 (si semplifica per 3);

= 7/2 + 1/1 + 3/8 + 1/8 - 7/4 = 

mcm(2; 8; 4) = 8;

= 28/8 + 8/8 + 3/8 + 1/8 - 14/8 =

= 26/8 = 13/4.  (Se non ho sbagliato i calcoli).

Ciao @marialuigia

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$\small \dfrac{7}{2}+1+\left[\dfrac{1}{8}+\left(\dfrac{1}{2}+\dfrac{11}{6}-\dfrac{3}{4}\right)-\left(\dfrac{5}{6}+\dfrac{8}{15}-\dfrac{1}{30}\right)\right]+\dfrac{1}{8}-\left(\dfrac{3}{2}+\dfrac{1}{4}\right) =  $

$\small = \dfrac{7}{2}+1+\left[\dfrac{1}{8}+\left(\dfrac{6+22-9}{12}\right)-\left(\dfrac{25+16-1}{30}\right)\right]+\dfrac{1}{8}-\left(\dfrac{6+1}{4}\right) =  $

$\small = \dfrac{7}{2}+1+\left[\dfrac{1}{8}+\dfrac{19}{12}-\dfrac{\cancel{40}^4}{\cancel{30}_3}\right]+\dfrac{1}{8}-\dfrac{7}{4} =  $

$\small = \dfrac{7}{2}+1+\left[\dfrac{1}{8}+\dfrac{19}{12}-\dfrac{4}{3}\right]+\dfrac{1}{8}-\dfrac{7}{4} =  $

$\small = \dfrac{7}{2}+1+\left[\dfrac{3+38-32}{24}\right]+\dfrac{1}{8}-\dfrac{7}{4} =  $

$\small = \dfrac{7}{2}+1+\dfrac{9}{24}+\dfrac{1}{8}-\dfrac{7}{4} =  $

$\small = \dfrac{84+24+9+3-42}{24} =  $

$\small = \dfrac{\cancel{78}^{13}}{\cancel{24}_4} =  $

$\small = \dfrac{13}{4}   $