a) (-15) +14+(-85)
b) 465 + [58 +(-465) +(-38)]
c) 160 – (6.5^2 – 3.2^3) + 2015^0
d) 2x + 5 =3^4 : 3^2
e) x – 7 =(-14) + (-8)
a) (-15) +14+(-85)
b) 465 + [58 +(-465) +(-38)]
c) 160 – (6.5^2 – 3.2^3) + 2015^0
d) 2x + 5 =3^4 : 3^2
e) x – 7 =(-14) + (-8)
`a) (-15) +14+(-85)`
`=[(-15)+(-85)]+14`
`=(-100)+14`
`=-86`
`b)465 + [58 +(-465) +(-38)]`
`=465+58-465-38`
`=(465-465)+(58-38)`
`=20`
`c)160 – (6.5^2 – 3.2^3) + 2015^0`
`=160-(6.25-3.8)+1`
`=160-(150-24)+1`
`=160-126+1`
`=34+1`
`=35`
`d)2x+5=3^4 : 3^2`
`→2x+5=3^(4-2)`
`→2x+5=3^2`
`→2x+5=9`
`→2x=9-5`
`→2x=4`
`→x=4:2`
`→x=2`
Vậy `x=2`
`e)x – 7 =(-14) + (-8)`
`→x-7=-22`
`→x=-22+7`
`→x=-15`
Vậy `x=-15`
`a)(–15)+14+(–85)` `b) 465+[58+(–465)+(–38)]`
`=[(–85)+(–15)]+14` `=465+[58+(–503)]`
`=(–100)+14` `=465+(–445)`
`=–86` `=20`
`c)160–(6.5^2–3.2^3)+2015^0` `d)2x+5=3^4÷3^2`
`=160–(150–24)+1` `=>2x+5=9`
`=160–126+1` `=>2x=9–5`
`=34+1` `=>2x=4`
`=35` ` =>x=4÷2`
`=>x=2`
`e)x–7=(–14)+(–8)`
`=>x–7=(–22)`
`=>x=(–22)+7`
`=>x=(–15)`