Đáp án:
`12`
`(x+1)+(x+2)+...+(x+50)=1475` (Có `50` số hạng)
`=>50x+(1+2+3+...+50)=1475`
`=>50x+((50+1).50)/2=1475`
`=>50x+1275=1475`
`=>50x=200`
`=>x=4`
Vậy `x=4`.
`3`
$x+(-36)=33-|-103|$
`=>x-36=33-103`
`=>x=33-103+36`
`=>`$x=-34$
Vậy $x=-34$.
`4`
$[(8x-12):4].3^6=3^9$
`=>`$(8x-12):4=3^3$
`=>`$(8x-12):4=27$
`=>8x-12=108`
`=>8x=120`
`=>x=15`
Vậy `x=15`.
`5`
`220+[2^4+(x-5)]=8^2 .5`
`=>220+[2^4+(x-5)]=320`
`=>2^4+(x-5)=100`
`=>16+(x-5)=100`
`=>x-5=84`
`=>x=89`
Vậy `x=89`.