Question 158600
Given {{{f(x) = 5x^2 - 5x }}}

Find 
f(0)
{{{f(0) = 5*0^2 - 5*0 }}}
{{{f(0) = 0 - 0 }}}
{{{f(0) = 0 }}}

Find 
f(-1)
{{{f(-1) = 5*(-1)^2 - 5*(-1) }}}
{{{f(-1) = 5*1 + 5*1 }}}
{{{f(-1) = 5 + 5 }}}
{{{f(-1) = 10 }}}

You get the idea?  You can do f(2)