y=x√(1+x^2)
y'=(x)'√(1+x^2)+x*(√(1+x^2))'
=√(1+x^2)+x*1/(2√(1+x^2))*(1+x^2)'
=√(1+x^2)+2x^2/(2√(1+x^2))
=√(1+x^2)+x^2/√(1+x^2)
y'(1)=√(1+1^2)+1^2/√(1+1^2)
=√2+1/√2
=√2+√2/2
=3√2/2