Question 626148
The complex zeros always come in pairs that 
look like {{{ a + b*i }}} and {{{ a - b*i }}}, so the 
pairs of factors are {{{ x - 5*i }}} and {{{ x + 5*i }}} 
If I multiply these, I get {{{ x^2 - 25*(-1) = x^2 + 25 }}}
------------
Now I divide {{{ 2x^3 + 3x^2 + 50x + 75 }}}
by {{{ x^2 + 25 }}} and I get {{{ 2x + 3 }}} as the 
3rd factor . Set it equal to zero.
{{{ 2x + 3 = 0 }}}
{{{ 2x = -3 }}}
{{{ x = -(3/2) }}}
Here's the plot:
{{{ graph( 500, 500, -10, 10, -200, 200, 2x^3 + 3x^2 + 50x + 75 ) }}}