Hello all my name is larsson and I am 30 years of age and am trying to teach myself Maths. I was able to do most of the questions in this section but the last few have me stumped

(the square root of x) + 1 = ( the square root of x + 9 )

It says these questions need squaring twice and the answer is 16 but I can't work it out.

Any help would be great

Thanks and regards

Larsson