👤

A= 7/4 x 3 + 8/5 x 3 + ..... 20/17 x 3 si b= 1/3x4 + 2/3x5 +3/3x6 +.....+14/3x17


Răspuns :

a = (3+4)/(3·4) + (3+5)/(3·5) + ......+(3+17)/(3·17)
a = 1/4 + 1/3 + 1/5 + 1/3 +...........+ 1/17 + 1/3
b = (4-3)/(3·4) + (5-3)/(3·5) + ......+ (17-3)/(3·17)
b = 1/3 - 1/4 + 1/3 - 1/5 +..........+ 1/3 - 1/17
a + b = 1/3 ·14 + 1/3 ·14 = 28/3