Question

Tìm X biết

a) |x+1|+|x+2|+|x+3|+...+|x+10|=11x

b) 2(x-1)-4(x-3)=2017

Answer 1

cho hỏi 11 x với gì vậy

Answer 2

a )Ta có :

|x + 1| ≥ 0

|x + 2| ≥ 0

|x + 3| ≥ 0

.......

|x + 10| ≥ 0

=> |x + 1| + |x + 2 | + .... + |x + 10| ≥ 0

Mà |x + 1| + |x + 2 | + .... + |x + 10| = 11x

=> 11x ≥ 0 => x ≥ 0

Vì x ≥ 0 => |x + 1| + |x + 2 | + .... + |x + 10| = x + 1 + x + 2 + ... + x + 10 = 11x

=> 10x + 55 = 11x => 11x - 10x = 55 => x = 55

b ) 2(x + 1) - 4(x - 3) = 2017

<=> 2x + 2 - 4x + 12 = 2017

<=> 2x - 4x + 2 + 12 = 2017

<=> - 2x + 14 = 2017

<=> -2x = 2003

=> x = -1001.5

Answer 3

a) x = 55

b) x = -1001,5

Answer 4

a, x = 55

b, x = - 1001, 5

~ hok tốt nha ~