ĐK : 6x \(\ge0\Rightarrow x\ge0\)
Khi đó |x + 1| = x + 1
|x + 2| = x +2
|x + 3| = x +3
|x + 4| = x + 4
|x + 5| = x +5
Khi đó |x + 1| + |x + 2| + |x + 3| + |x + 4| + |x + 5| = 6x
<=> x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 6x
<=> 5x + 15 = 6x
<=> x = 15 (tm)
Vậy x = 15
b) 3x + 2 - 3x + 1 - 3x = 15.340
=> 3x(32 - 3 - 1) = 15.340
<=> 3x . 5 = 15.340
<=> 3x = 341
<=> x = 41
Vậy x = 41
a,vì /x+1/,/x+2/,/x+3/,/x+4/,/x+5/\(\ge\)0 mà /x+1/+/x+2/+/x+3/+/x+4/+/x+5/=6x suy ra x>0
nên /x+1/+/x+2/+/x+3/+/x+4/+/x+5/=x+1+x+2+x+3+x+4+x+5=6x ( giải thích: /x/=x khi x \(\ge0\))
suy ra 5x+21=6x suy ra x=21
b, \(3^{x+2}-3^{x+1}-3^x=15.3^{40}\)
suy ra \(3^x\left(9-3-1\right)=5.3^{41}\)
suy ra \(3^x.5=5.3^{41}\Rightarrow x=41\)