Question 588620
Unless your teacher is mean, you left out a zero.
{{{0.04y^2-0.0025}}} is easy to factor because it is the difference of two squares.
{{{0.04y^2=(0.2y)^2}}} and {{{0.0025=0.05^2}}} so
{{{0.04y^2-0.0025=(0.2y+0.05)(0.2y-0.05)}}}
If the problem is really {{{0.4y^2-0.0025}}} you would end up with ugly square roots in your factors, as in
{{{0.4y^2-0.0025=0.4(y^2-0.00625)=0.4(y+0.025sqrt(10))(y-0.025sqrt(10))}}}
or if you like it better
{{{(0.4y+0.01sqrt(10))(y-0.025sqrt(10))}}} or {{{(y+0.025sqrt(10))(0.4y-0.01sqrt(10))}}}