Calculeaza :a) suma nr 3,72 și, 2,2;b) nr de 100 de ori mai mic decât 258;c) 2 supra 7 ×14 supra 10 +4 supra 9 ÷10 supra 9 +5^2 supra 5&3;d) ( 1 supra 2 -1 supra 8)×2^4; e)1supra 201+ 2 supra 201 +...+201 supra 201 f) (1+1,8^2×100)÷(2,4×15-0,1^3×1000×11)g) 5,2+5, (2)-5,02-5,0 (2).
Răspunsuri la întrebare
a) 3,72 + 2,2 = 5,92
b) 258:100 = 2,58
c) 2/7×14/10 + 4/9:10/9 + 5²/5³ = 2/5 + 4/9×9/10 + 1/5 = 3/5+2/5 = 5/5 = 1
d) (1/2 - 1/8)×2⁴ = (4/8 - 1/8)×16 = 3/8×16 = 24
e) 1/201 + 2/201 + ..... + 201/201 = (1+2+3+......+201)/201 = S/201
Aflăm pe S prin formula lui Gauss
S = (1+201)×201/2 = (202×201)/2 = 101×201 = 20301
⇒20301/201 = 101
f) (1 + 1,8²×100) : (2,4×15 - 0,1³×1000×11) = (1 + 3,24×100) : (36 - 0,001×11000) = (1 + 324) : (36 - 11) = 325:25 = 13
g) 5,2 = 52/10 = 26/5
5,(2) = (52-5)/9 = 47/9
5,02 = 502/100 = 251/50
5,0(2) = (502-50)/90 = 452/90 = 226/45
5,2 + 5,(2) - 5,02 - 5,0(2) = 26/5 + 47/9 - 251/50 - 226/45
Ducem la acelasi numitor comun 450 (26/5 amplifici cu 90, 47/9 cu 50, 251/50 cu 9, 226/45 cu 10)
(2340 + 2350 - 2259 - 2260)/450 = 171/450 = 57/150 = 19/50