The correct answer is B
Hope this helped :)
Answer:
hence cos ( 2 A ) = cos 2 A − ( 1 − cos 2 A ) = 2 cos 2 A − 1
Step-by-step explanation:Well we know that for two angles A , B
it holds that cos ( A + B ) = cos A cos B − sin A ⋅ sin B hence for A = B you get cos ( 2 A ) = cos 2 A − sin 2 A But sin 2 A = 1 − cos 2 A
Answer: C. 
Step-by-step explanation:
Given: Box contains 8 green balls and 4 purple balls.
Total balls = 8+4 = 12
event 1 = first picking green ball
event 2 = second picking purple balls.
As first ball was replaced, that means both events are independent.
Probability that you have selected a green ball and then a purple ball = P(purple ball )
Formula for probability = 
Probability of selecting a purple ball (second pick)= 

The required probability
, so C is correct option.
Answer:i√6/6 , -i√6/6
Step-by-step explanation:
6x^2+5-4=0
6x^2=-5+4
x=√-1/6
x=±i√1/60=±i√1/√6*(√6/√6)=±i√6/6
Step-by-step explanation:
6. 7x + 7y = -11
7. -1x + 8y = 12
8. 9x + 11y = -7