The idea behind the problem is solving an equation involving square roots. The equation I'm talking about is
[tex]358=20\cdot\sqrt[]{273+t}[/tex]
(I merely replaced v by 358; what we are supposed to do is to find t). Let's solve it:
1. 20 is multiplying at the right-hand side, let's send it to divide at the left:
[tex]\frac{358}{20}=\sqrt[]{273+t}[/tex]
2. (this is the most important step) Take the power of 2 on both sides:
[tex](\frac{358}{20})^2=273+t[/tex]
...........................................................................................................................................................
Comment: Remember that
[tex](\sqrt[]{273+t})^2=273+t[/tex]
because square root and powering by two are inverse of each other.
...........................................................................................................................................................
3. Put the left-hand side in a calculator to get:
[tex]\frac{128164}{400}=273+t[/tex]
4. Let's subtract 273 to the left-hand side:
[tex]320.41-273=t[/tex][tex]47.41\degree C=t[/tex]
