$2cosx+2cos2x=0 \\ -2sin^2x+2cos^2x+2cosx=0 \\ -2(1-cos^2x)+2cos^2x+2cosx=0 \\ -2+2cos^2x+2cos^2x+2cosx=0 \\ 4cos^2x+2cosx-2=0 \\ t=cos x \\ 4t^2+2t-2=0 \\ \Delta=4+32=36 \\ t_1= \frac{-2-6}{8}=-1 \\ t_2= \frac{-2+6}{8}= \frac{1}{2} \\ cos x=-1 \lor cos x= \frac{1}{2} \\ x=-\pi \lor x= \frac{5\pi}{3}$

6 0

3 years ago

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The area of a rectangle is 8w + 18 square feet. The length of the rectangle is 2 feet. Use factoring to write an expression to r

qwelly [4]

Answer:

4w + 9

Step-by-step explanation:

Area of rectangle = length x width (or base x height, depending on how you look at it).

It is given to you that:

Area = 8w + 18

Length = 2

Let: width = x

Plug in the corresponding terms with the corresponding words:

8w + 18 = 2x

Isolate the variable, x. Divide 2 from both sides of the equation:

(8w + 18)/2 = (2x)/2

x = (8w + 18)/2

w = (8w)/2 + (18)/2

w = 4w + 9

4w + 9 is the expression that represents the width of the rectangle.

6 0

3 years ago

How do I find B in y=mx+b?

mixas84 [53]

If you already have an equation, all you have to do is locate the slope and look after it. But if it's in a graph, it's where the line is crossing the y-axis.

An example of the equation would be

y=2x+3
y=mx+b
2 would be m which is slope
and 3 would be b which is the y-intercept

3 0

3 years ago