[tex]\displaystyle x=3(1+2+3+...+49)+1225 \\ \\ x=3 \cdot \frac{49(49+1)}{2} +1225 \\ \\ x=3 \cdot \frac{49 \cdot 50}{2} +1225 \\ \\ x=3 \cdot 49 \cdot 25+1225 \\ \\ x=147 \cdot 25+1225 \\ \\ x=3675+1225 \\ \\ x=4900 \\ \\ \sqrt{x} = \sqrt{4900} =70[/tex]
