If a parabola that opens upwards now opens downwards, what change to y = a (x — h)2 + k has occurred?

Answer 1

change y to -y

change y = a(x-h)^2 + k to

-y = a(x-h)^2 +k

or

y = -a(x-h)^2 -k

change the sign of "a" the coefficeint of the x^2 term

it flips the parabola upside down

change y = a(x-h)^2 +k

to y = -a(x-h)^2 -k

where a>0

unless you want to keep the vertex the same

then

change

y =a(x-h)^2 +k

to

y =-a(x-h)^2 +k