x + (x - 1) + (x - 2) + ... + (x - 50) = 255
=> (x + x + x + ... + x) - (0 + 1 + 2 + ... + 50) = 255
51 số x 51 số hạng
=> 51x - (0 + 50).51:2 = 255
=> 51x - 50.51:2 = 255
=> 51x - 25.51 = 255
=> 51.(x - 25) = 255
=> x - 25 = 255 : 51
=> x - 25 = 5
=> x = 5 + 25
=> x = 30
Vậy x = 30
Tim x biet: (|x+2|-3).(x^2016+1) be hon
hoac bang 0
Tim x biet
A, x/15 = x-2/30
B, 7/8 < x/80 < 9/10
C, 1/6 < 5/x < 1/4
tim x, y biet
x/49=-3/7
b, x-2/12=2/3
c,x-1/9=x+3=15
d,3/x=9/35=-36/84
tim x thuoc Z,biet : (x-1).(xy+3)
bai 1, tim x thuoc Z, biet
a,3a+2 chia hết cho x-1
b, x^2 +2 * x - 7 chia hết cho x+2
c, x^2 + x + 1 chia hết cho x+1
d, 32-8 chia hết cho x- 4
e, x+5 chia hết cho x-2
g, 2x chia hết cho x-1
Tim x biet
A, 5/9 + x/-1 = -1/3
B, 1/5 + 2/20 + 121/165 <x< 1/2 + 156/72 + 1/3 ( x thuoc N)
C, x + 5/3 = 1/81
D, x-1/3 + 3x-5/2 + 2x/9 + -5x+3/9 = 210/420
tim x, biet:
a,|\(\dfrac{3}{2}\)x+\(\dfrac{1}{2}\)|=|4x-1|
Tim so nguyen x biet
X X * XX =625
biet X X o so bi chia va so chia giong nhau
tim x,y thuoc z biet (x-2).(y+12)<0