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3 years ago

Need help! Find the area

Mathematics

1 answer:

sammy [17]3 years ago

7 0

7. the formula for octagon is a=2(1+radical2)s^2
s=4
a=about 77.25
8.

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Which of the following functions are solutions of the differential equation y'' + y = 3 sin x? (select all that apply)

DiKsa [7]

Answer:

Step-by-step explanation:

We must compute the derivatives and check if the equation is satisfied.

A. $y'=(3\sin x)'=3\cos x$ . Differentiate again to get $y''=(3\cos x)'=-3\sin x$ , then $y''+y=-3\sin x+3\sin x=0\neq 3\sin x$ so this choice of y doesn't solve the equation.

B. $y'=3\sin x+3x\cos x-5\cosx +5x\sin x=(5x+3)\sin x+(3x-5)\cos x$ and $y''=5\sin x+(5x+3)\cos x+3\cos x-(3x-5)\sin x=(10-3x)\sin x+(5x+6)\cos x$ , then $y''+y=10\sin x+6\cos x\neq 3\sin x$ so y is not a solution

C. $y'=\frac{-3}{2}\cos x+\frac{3}{2}x\sin x$ hence $y''=\frac{3}{2}\sin x+\frac{3}{2}\sin x+\frac{3}{2}x\cos x=3\sin x+\frac{3}{2}x\cos x$ . Then $y''+y=3\sin x+\frac{3}{2}x\cos x-\frac{3}{2}x\cos x=3\sin x$ so y is a solution.

D. $y'=-3\sin x$ and $y''=-3\cos x$ , then $y''+y=0$ thus y isn't a solution

E. $y'=\frac{3}{2}\sin x+\frac{3}{2}x\cos x$ hence $y''=\frac{3}{2}\cos x+\frac{3}{2}\cos x-\frac{3}{2}x\sin x=3\cos x-\frac{3}{2}x\cos x$ . Then $y''+y=3\cos x-\frac{3}{2}x\cos x-\frac{3}{2}x\cos x=3\cos x\neq 3\sin x$ then y is not a solution.

3 0

3 years ago

The ratio of minutes to dry and minutes to

Mnenie [13.5K]

Answer:

56:42 (i hope this is right)

Step-by-step explanation:

I divided 56 and 4 which makes 14. Then I multiplied 14 and 3 to get 42. So 56 by 42.

3 0

3 years ago

Round 12.5478 to the nearest hundredths

solong [7]

Answer:

12.04

Step-by-step explanation:

Find the number in the hundredth place 4 and look one place to the right for the rounding digit 1 . Round up if this number is greater than or equal to 5 and round down if it is less than 5 .

6 0

3 years ago

I need the answer and the work! <br> you have to find n.

zloy xaker [14]

Tell you what I'll do: I'll show you the work, for two of them.
Then, knowing how to do it, you'll find the answers.
Deal ?

#1). n + (-13) = -12

Remove the parentheses
on the left side: n - 13 = -12

Add 13 to each side: n = 1

================================

#3). -15 + n = 3

Add 15 to each side: n = 18

OK. Look those over, understand how they're done, then TAKE IT !

6 0

3 years ago

How to i put <img src="https://tex.z-dn.net/?f=y%5E%7B2%7D%20%2B20x%2B8y%2B156%3D0" id="TexFormula1" title="y^{2} +20x+8y+156=0"

Svetllana [295]

Answer:

y=−4+2√5(−x−7)

y=−4−2√5(−x−7)

4 0

2 years ago