Question

Tìm x :

a, x+ ( x-1 ) + (x -2 ) +......+(x-50 ) =255

b, 3+6+9+.......+x=630

c,3.x - x + \(\frac{1}{2}\).x = 5\(\frac{1}{3}\)

           Ai làm nhanh mk tích cho !!!!!!!!

Answer 1

a. x + (x - 1) + (x - 2) + ... + (x - 50) = 255

=> x + x - 1 + x - 2 + ... + x - 50 = 255

=> 51.x - (1 + 2 + ... + 50) = 255

=> 51.x - (50 + 1).50:2 = 255

=> 51.x - 1275 = 255

=> 51.x = 255 + 1275

=> 51.x = 1530

=> x = 30

b. 3 + 6 + 9 + ... + x = 630

Số số hạng: (x - 3) : 3 + 1 = x /3 (số hạng)

=> (x + 3).(x/3):2 = 630

=> (x + 3).(x/3) = 1260

=> x.(x +3)/3 = 1260

=> x.(x + 3) = 3780

=> x.(x + 3) = 60.63

=> x.(x + 3) = 60.(60 + 3)

=> x = 60

c. 3.x - x + 1/2.x = 5\(\frac{1}{3}\)

=> x.(3 - 1 + 1/2) = 16/3

=> x.5/2 = 16/3

=> x = 16/3 : 5/2

=> x = 16/3 . 2/5

=> x = 32/15

Answer 2

 x+(x-1)+(x-2)+............+(x-50)= 255

=> (x-50)+(x-49)+(x-48)+............+x=255

=> (x+x-50).51:2=255

=> (x+x-50).51=255.2

=> 2x-50=510:51

=> 2x=10+50

=> x=60:2

=> x=30

Answer 3

x=30 k nhe 

Answer 4

\(x+\left(x-1\right)+\left(x-2\right)+...+\left(x-50\right)=255\)

Answer 5

x=30 đó