Răspuns:
Explicație pas cu pas:
a)
[(3x - 2)*2/3 + 3/2]*6/5 = 3
(3x - 2)*2/3 + 3/2 = 3 : 6/5 = 3*5/6 = 5/2
(3x - 2)*2/3 = 5/2 - 3/2 = 2/2 = 1
3x - 2 = 1 : 2/3 = 1*3/2 = 3/2
3x = 2 + 3/2 = 4/2 + 3/2 = 7/2
x = 7/2 : 3 = 7/6
b)
375 - (a - 25) = 300
a - 25 = 375 - 300 = 75
a = 25 + 75 = 100
c)
1 + 2 + 3 + ...+ x = 55
1 + 2 + 3 + 4 = 10
1 + 2 + 3 + 4 + 5 = 15
1 + 2 + 3 + 4 + 5 + 6 = 21
1 + 2 + 3 + 4 + 5 + 6 + 7 = 28
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55
x = 10
daca ai invatat progresii arimetice poti aplica si formulele de acolo ca sa il calculazi pe x
