Algebra

$y = -2x^2 + 8x - 15 - 3x^2 - 14x + 25$

 

First, let's simplify the equation a bit so we get a nice quadratic equation in standard form: $y = -5x^2-6x+10$.

 

There are a lot of ways to find the vertex of a parabola, but the easiest way is to use the formula $x=-b/2a$ and then plug that x-value into the equation to solve for $y$.

 

From the formula, $x=-6/10=-3/5$

 

Now we can substitute this $x$ value into the original equation: $y=-5*9/25+18/5+10=9/5+10=59/5$

 

Therefore, the vertex of the equation is $(-3/5,59/5)$. You can even see this if you use a graphing calculator.