JEE MATHEMATICS MCQ: INCREASING & DECREASING

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Analyzing +4 | -1

f\left( x \right) = 2{x^3} + 9{x^2} + \lambda \;x + 20

is a decreasing function of x in the largest possible interval

\left( { - 2,\; - 1} \right),

then

\lambda =

View answer and explanation

Correct option: A

Option A (12) is correct because the function is decreasing in the interval (-2, -1) only when the derivative is negative and the roots of the derivative equation are -2 and -1.

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If the function

f\left( x \right) = \frac{{K\sin x + 2\cos x}}{{\sin x + \cos x}}

is increasing for all values of

x

, then The set of values of a for which the function

f\left( x \right) = {x^2} + ax + 1

is an increasing function on [1,2] is The value of

a

in order that

f(x)=

\sin x-\cos x-a x+b

decreases for all real values is given by The function

f(x)=x e^{x(1-x)}, x \in R

, is If

f

and

g

are two increasing functions such that

fog

is defined, then If

f\left( x \right) = {x^3} + b{x^2} + cx + d

and

0 < {b^2} < c

, then in

\left( { - \infty ,\;\infty } \right)