Question

Given that the greatest value of k+8x-2x^2 is 9,find the value of the constant k?

Answer 1

k+8x-2x²
Greatest value is 9
Let 9 be a root of the equation
then, -2(9²)+8(9)+k=0
-162+72+k=0
-90+k=0
k=90

Answer 2

Answer:

Step-by-step explanation:

As we know that the highest value can only be fine through its y axis value .so to find the y coordinate we use the formula of vertex formula .y=c-(b^2/4a).

In the avobe question y=-2x^2+8x+k

a= - 2 ,b=+8 c=k

the greatest point is 9.that is y value .

y=c-(b^2/4a)

9=K-(8^2/4*-2)

k=1

the value for k=1.Answer.