Toán Lớp 6: Tìm x
|x+1|+|x+2|+|x+3|+|x+4|=100
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Toán Lớp 6: Tìm x
|x+1|+|x+2|+|x+3|+|x+4|=100
Comments ( 2 )
Ta có:
Vì:
|x+1|\geq0 ∀x
|x+2|\geq0 ∀x
|x+3|\geq0 ∀x
|x+4|\geq0 ∀x
=>
|x+1|=x+1
|x+2|=x+2
|x+3|=x+3
|x+4|=x+4
=>x+1+x+2+x+3+x+4=100
=>(x+x+x+x)+(1+2+3+4)=100
=>4x+10=100
=>4x=100-10
=>4x=90
=>x=90:4
=>x=22,5
Vậy x=22,5