The maximum value for 7 + 10x – 5x^2is

BPSC 48th to 52nd Exam Prelims 2008 Solved Paper

Question : 31 of 150

Marks: +1, -0

The maximum value for

7 + 10x – 5x^2

Solution:

From the question

y=7+10 x-5 x^{3}

=0

Value of y will be maximum if

\;{d y}/{d x}

\;{d y}/{d x}=0+10-10 x=0

⇒ x=1

\;{d^{2} y}/{d x^{2}}=-10<0

So, at

x=1, y

will be maximum

y=7+10(1)-5(1)^{3}

=12

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