MHT CET2012MathematicsApplication of Derivatives
Divide 10 into two parts such that the sum of double of the first and the square of the second is minimum
Options
- A(6,4)
- B(7,3)
- C(8,2)
- D(9,1)
Correct answer
D. (9,1)
Step-by-step solution
Let x and y be the two parts of the number 10 . +y=10 (i) According to the question, Let aligned A &=2 x+y² &=2 x+(10-x)² &=2 x+100+x²-20 x &=x²-18 x+100 aligned On differentiating w.r.t. x , we get d A d x =2 x-18 For max or min of A , Put d A d x =0=2 x-18 =9 Now, d² A d x² =2>0 ( ) On putting x=9 in Eq. (i), we get y=1 (x, y)=(9,1)