Question

[Nguyễn Bá Lâm]

giúp mình với

Answer 1

[Yen Nhi]

`Answer:`

1. 

a. \(45^{15}:45^{14}:9:5=45:9:5=5:5=1\)

b. \(\left(9+2\right)^2+\left(9-2\right)^2-\left(1^2-2^3\right)=11^2+7^2-\left(1+8\right)=121+49-9=161\)

c. \(2.4.8.16.32.64.128.256.512.1024:2^{52}\)

\(=2.2^2.2^3.2^4.2^5.2^6.2^7.2^8.2^9.2^{10}:2^{52}\)

\(=2^{1+2+3+4+5+6+7+8+9+10}:2^{52}\)

\(=2^{55}:2^{52}\)

\(=8\)

2.

a. \(87-\left(73-x\right)=20\)

\(\Leftrightarrow73-x=87-20\)

\(\Leftrightarrow73-x=67\)

\(\Leftrightarrow x=73-67\)

\(\Leftrightarrow x=6\)

b. \(15+\left(x+2\right)^2:3=18\)

\(\Leftrightarrow\left(x+2\right)^2:3=18-15\)

\(\Leftrightarrow\left(x+2\right)^2=3.3\)

\(\Leftrightarrow\left(x+2\right)^2=3^2\)

\(\Leftrightarrow x+2=3\)

\(\Leftrightarrow x=3-2\)

\(\Leftrightarrow x=1\)

c. \(3^{x-1}+3^x+3^{x+1}=39\)

\(\Leftrightarrow3^x.3^{-1}+3^x.3^1+3^x.3^1=39\)

\(\Leftrightarrow3^x.\left(\frac{1}{3}+1+3\right)=39\)

\(\Leftrightarrow3^x.\frac{13}{3}=39\)

\(\Leftrightarrow3^x=39:\frac{13}{3}\)

\(\Leftrightarrow3^x=\frac{117}{12}\)

\(\Leftrightarrow3^x=3^2\)

\(\Leftrightarrow x=2\)