Question

Ix+1I+Ix+2I+Ix+3I........+Ix+20I=25x

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Answer 1

Tách x ra ta được :

20x + ( 1 + 2 + ... + 20) = 25x

1 + 2 + ... +20= 20 x (20+1) : 2 = 210

20x+210=25x

5x=210

x=42

Answer 2

tyhtrdfgtdrthth

Answer 3

vì | x + 1 | \(\ge\)0 ; | x + 2 | \(\ge\)0 ; ... ;  | x + 20 | \(\ge\)0

\(\Rightarrow\)| x +1 | + | x + 2 | + ... + | x + 20 | \(\ge\)0 nên 25x \(\ge\)0

Ta có : ( x + 1 ) + ( x +2 ) + ... + ( x + 20 ) = 25x

( x + x + ... + x ) + ( 1 + 2+ ... + 20 ) =25x

20x + 210 = 25x

5x = 210

x = 42