1)Aflati pe x din: a) 34-2·(2 660 + 76 : x) : 893 = 28 b) 51-(2 600 : 76 + x) : 23 = 28
2) Determinati nr. x din: a) (100-x:75)·35+1=876 b) [(100+x:75-1)]·35=875
3)Calcati 2017 stiind ca :
x ·2 -> +10 -> : 5 -> 10
Dau coroana rpd pls
Răspunsuri la întrebare
1) a)
34 - 2 × ( 2 660 + 76 : x ) : 893 = 28
2 × ( 2 660 + 76 : x ) : 893 = 34 - 28
2 × ( 2 660 + 76 : x ) : 893 = 6
2 × ( 2 660 + 76 : x ) = 6 × 893
2 660 + 76 : x = 5 358 : 2
2 660 + 76 : x = 2 679
76 : x = 2 679 - 2 660
76 : x = 19
x = 76 : 19
x = 4 → numarul aflat prin metoda mersului invers
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b) Corectie: 2 600 nu se imparte exact la 76, astfel ca voi modifica
pe 2 600 cu 2 660 !
51 - ( 2 660 : 76 + x ) : 23 = 28
( 35 + x ) : 23 = 51 - 28
( 35 + x ) : 23 = 23
35 + x = 23 × 23
35 + x = 529
x = 529 - 35
x = 494 → numarul aflat prin metoda mersului invers
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2) a)
( 100 - x : 75 ) × 35 + 1 = 876
( 100 - x : 75 ) × 35 = 876 - 1
( 100 - x : 75 ) × 35 = 875
100 - x : 75 = 875 : 35
100 - x : 75 = 25
x : 75 = 100 - 25
x : 75 = 75
x = 75 × 75
x = 5 625
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b) Iata care era forma corecta a exercitiului :
[ ( 100 + x ) : 75 - 1 ] × 35 = 875
( 100 + x ) : 75 - 1 = 875 : 35
( 100 + x ) : 75 - 1 = 25
( 100 + x ) : 75 = 25 + 1
( 100 + x ) : 75 = 26
100 + x = 26 × 75
100 + x = 1 950
x = 1950 - 100
x = 1 850 → numarul, aflat prin metoda mersului invers
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3)
( x · 2 + 10 ) : 5 = 10
x · 2 + 10 = 10 × 5
x · 2 = 50 - 10
x = 40 : 2
x = 20