cos4x = cos2x
We know that:
cos2x = 1-2cos^2 x
==> cos4x = 1-2cos^2 (2x)
Now substitute:
==> 1-2cos^2 (2x) = cos2x
==> 2cos^2 (2x) + cos2x - 1 = 0
Now factor:
==> (2cos2x -1)(cos2x + 1) = 0
==> 2cos2x -1 = 0 ==> cos2x =1/2 ==> 2x= pi/3
==> x1= pi/6 , 7pi/6
==> x1= pi/6 + 2npi
==> x2= 7pi/6 + 2npi
==> cos2x = -1 ==> 2x= pi ==> x3 = pi/2 + 2npi.
<span>==> x= { pi/6+2npi, 7pi/6+2npi, pi/2+2npi}</span>
Answer:
C) 2/5×1/4
Step-by-step explanation:
Dividing by a number is the same by multiplying by the reciprocal of the number.
For Example:
1/2 divided by 3 would be the same as 1/2 x 1/3
So for this problem we are given that 2/5 is divided by 4 which would be the same as 2/5 multiplied by the reciprocal of 4 which is 1/4 and thus the answer is option C which is 2/5×1/4
Answer:
2.8 in a half years
Step-by-step explanation:
Answer:
d = 50h
Step-by-step explanation:
distance = speed × time
Lumpy's distance (d) in miles, after driving h hours at 50 miles per hour, is given by ...
d = 50h
