Question 146616
Let's call the original length, S.
{{{(S+4)^2=49}}}
{{{S^2+8S+16=49}}}
{{{S^2+8S-33=0}}}
You can factor that into,
{{{(S+11)(S-3)=0}}}
Since a negative length would not make sense, we will only use the positive result.
{{{S-3=0}}}
{{{S=3}}}
The length of the original side was 3 m.