Question

g(x)=cos2x+4 show that g(2x)+g(–2x)=2g(2x)​

Answer 1

Answer:

Solution

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We have f(x)=cos(2x+

4

π

)

dx

dy

=−2sin(2x+

4

π

)

Since,

8

3π

<x<

8

7π

⇒

4

3π

<2x<

4

7π

⇒π<2x+

4

π

<2π

i.e 3

rd

and 4

th

quadrant

So, sin(2x+

4

π

) is negative

⇒

dx

dy

is positive

Hence, f(x) is increasing in the given interval