: Đẳng thức nào sau đây đúng ? A. cos4x – sin4x = 2-cos2x B. cos4x – sin4x = 1+2sin2x
1 answer:
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Answer:
The correct answer is: Option D) 5
Step-by-step explanation:
Given equation is:
In order to find that which values of x makes the equation true, we have to put each value of x in the equation. When both sides of equations will be equal, that value of x will be true for the equation.
Putting x = 2
Putting x = 3
Putting x=4
Putting x = 5
The equation is true for x = 5
Hence,
The correct answer is: Option D) 5