Question

For the given quadratic function use the method of "completing the square" to convert to a-h-k form, and then identify the vertex.

r(s)= -7s^2 +42s-33=_______________________

has its vertex at (______,________) .

Answer 1

factor out the -7in the first two terms, then complete the square, don't forget to add and subtract it and don't forget the -7

Answer 2

there is an easier way than completing the square
you know it is going to look like
\[r(s)=-7(r-h)^2+k\] and the vertex will be \((h,k)\)
vertex is always at \(-\frac{b}{2a}\) which in your case is \(-\frac{42}{2\times (-7)}=3\)

Answer 3

so you know it is going to be
\[r(s)=-7(s-3)^2+k\] and to find \(k\) replace \(s\) by \(3\) in the original expression and compute \(r(3)\)