[tex] (-x^{2} +5)-(3-4 x^{2} )[/tex]
To simplify this, use the FOIL method. First, Outer, Inner, Last.
First: Multiply the first numbers in each set of parentheses.
[tex]-x^{2} *-3=3 x^{2}[/tex]
Outer: Multiply the two outermost numbers in the equation.
[tex]-x^{2} *-4 x^{2} =5 x^{4}[/tex]
Inner: Multiply the two innermost numbers in the equation.
[tex]5*-3=-15[/tex]
Last: Multiply the last numbers in each set of parentheses.
[tex]5*-4 x^{2} =-20 x^{2} [/tex]
Then, we put them all together in an equation, from the highest exponent to the lowest, then highest prefix (number before the variable) to lowest.
[tex]5 x^{4} -20 x^{2} +3 x^{2} -15[/tex]
And simplify.
[tex]5 x^{4} -17 x^{2} -15[/tex]