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lys-0071 [83]
3 years ago
15

Please solve the eqution Cos4x + cos2x - 2 =0

Mathematics
1 answer:
horrorfan [7]3 years ago
6 0

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>

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kifflom [539]

<u>Answer: </u>

Option (c)

The average speed between 2.8 km and 4.2 km is 42 km/h

<u>Explanation:</u>

Given, the distance between 2.8 km and 4.2 km is 4.2 - 2.8 = 1.4 km

Time (in hours) between 2.8 km and 4.2 km

    = 0.084 – 0.051

     = 0.033 hr

Speed =\frac{Distance}{Time}

Speed = \frac{1.4}{0.033}

Speed = 42.4 km/hr = 42 km/h (rounded to nearest)

Therefore, the average speed between 2.8 km and 4.2 km is 42 km/hr

Hence, Option (C) is correct

4 0
3 years ago
2.16 repeating as a mixed number and fraction
MrMuchimi
2 16/100 this would be that as a fraction. I'm a little confused as to what your asking

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3 years ago
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The school that Stefan goes to is selling tickets to a choral performance. On the first day of ticket sales the school sold 3 se
aniked [119]
52 - 38 is 14 
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if 3 senior citizen tickets but 14$ = 38 
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3 years ago
Is the equation y=x+1 / x²+1 in simplest form? Explain how you can tell.
Lana71 [14]

According to the question, the equation \frac{x+1}{x^{2} +1} is the algebraic equation as well as polynomial equation. Using square root principles, the equation can be re-write.

The factors of the denominator term is not possible and it cannot be simplified. And the simplification is possible with the concept of complex number.

What is polynomial expression?

Polynomial expression are those equation whose highest degree is two. It is also called as quadratic equation. And it is simplified by performing the factors on the given expressions.

To learn more about the polynomial expression from the given link:

<u>brainly.com/question/1280754</u>

#SPJ4

8 0
1 year ago
If x + y = 12 and xy = -5, calculate the value of 1/x + 1/y.​
Paul [167]

\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{y}{xy}+\dfrac{x}{xy}=\dfrac{x+y}{xy}=\dfrac{12}{-5}=-\dfrac{12}{5}=-2,4

8 0
3 years ago
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