Question

find the maximum and minimum of:
y= 7+3x-2x^(2)

Answer 1

got a clue how to the max and min?

Answer 2

yeah....
first is to know its first derivative which is:
y'=-4x + 3
but i don't know how can i get its' critical values...

Answer 3

critical points is when you set the derivative equal to 0
y'=0=-4x+3
solve for x and find y(x)

just by looking at the function, we know its a parabolic curve, meaning there's either a maximum or a minimum, unless you have boundries
so you just need to determine whether (x,y(x)) is a maximum or a minimum

Answer 4

i meant parabola

Answer 5

so....
x=3/4
then, y= 65/8
but how to find the minima & maxima?

Answer 6

is it necessarily to have two critical values?

Answer 7

if you had x^3+..., then you would have 2 critical values, but for parabolas, theres only 1 max/min