Bài 1:
a: -124+24=-100
b: =37x100=3700
c: =198+60+302=500+60=560
d: =25+200:10
=25+20
=45
Bài 2:
a: \(\Leftrightarrow x=-65+10=-55\)
b: =>x-4=3
hay x=7
c: \(\Leftrightarrow-125+x+125=-25\)
hay x=-25
Bài 5:
\(a,3A=3^2+3^3+...+3^{101}\\ \Rightarrow3A-A=3^2+3^3+...+3^{101}-3-3^2-...-3^{100}\\ \Rightarrow2A=3^{101}-3\\ \Rightarrow2A+3=3^{101}=3^{4n+1}\\ \Rightarrow4n+1=101\\ \Rightarrow n=25\)
\(b,x^2+1=6y^2+2\\ \Rightarrow x^2=6y^2+1\)
\(\Rightarrow x\) lẻ
Mà \(x^2-1=6y^2\Rightarrow\left(x-1\right)\left(x+1\right)=6y^2\)
Mà x lẻ nên \(\left(x-1\right)\left(x+1\right)⋮8\Rightarrow6y^2⋮8\Rightarrow y\in B\left(2\right)\)
Mà y nguyên tố nên \(y=2\)
\(\Rightarrow x^2-24=1\Rightarrow x^2=25\Rightarrow x=5\left(snt\right)\)
Vậy \(\left(x;y\right)=\left(5;2\right)\)
