Question

what is the minimum value of (x - 9)(x-2)=?

(A)0
(B)49/4
(C) - 49/4
(D) 9​

Answer 1

Answer:

 Option C -49/4 Is Correct!!

Step-by-step explanation:

(x -2) (x -9)

= (x^2 2x - 9x + 18)

=(x^2 - 11x + 18)

= x^2 - 11x + 121/4 - 121/4 + 18

(x - 11/2)^2 - 49/4

x = 11/2 = -49/4

Hence,Proved Option C is correct!

Answer 2

Answer:

(x-9)(x-2)=fx

fx=x²-11x+18

derivative ,

2x-11=f'x

let f'x=0, for max or min values

x=11/2

second derivative,=0(+ve)

let x=11/2,in equation

(11/2 -9)(11/2 -2)=fx

fx= -7/2 ×(7/2)= -49/4(minimum value)

option c is correct