6²-x²=5²-（5-x）²

6²-x²=5²-（5-x）²
6²-x²=5²-（5-x）²

6²-x²=5²-（5-x）²
36-x^2=25-(x^2-10x+25)
36-x^2=-x^2+10x
36=10x
x=3.6

x=3.6

36-x^2=25-25+10x-x^2
10x=36
x=18/5

36-x²=25-(25-10x+x²)