5.22+(x+3)=52
5.4+(x+3)=25
20+(x+3)=25
⇒x+3=5
⇒x=2
\(5.2^2+\left(x+3\right)=5^2\Rightarrow5.4+\left(x+3\right)=25\Rightarrow4+\left(x+3\right)=25:5\Rightarrow4+\left(x+3\right)=5\Rightarrow x+3=5-4\Rightarrow x+3=1\Rightarrow x=3-1\Rightarrow x=...\)
5.22+(x+3)=52
20+(x+3)=25
x+3=25-20
x+3=5
x=5-3
x=2