Ngths. Find Complete the fact Triangle. Write

The choir teacher is arranging the Junior and Senior choir members in equal rows for an upcoming concert. Each row will contain

ANTONII [103]

The answer is 9

both 81 and 63 are dividable by 9, and nothing higher

7 0

3 years ago

<img src="https://tex.z-dn.net/?f=%24a%2Ba%20r%2Ba%20r%5E%7B2%7D%2B%5Cldots%20%5Cinfty%3D15%24%24a%5E%7B2%7D%2B%28a%20r%29%5E%7B

riadik2000 [5.3K]

Let

$S_n = \displaystyle \sum_{k=0}^n r^k = 1 + r + r^2 + \cdots + r^n$

where we assume |r| < 1. Multiplying on both sides by r gives

$r S_n = \displaystyle \sum_{k=0}^n r^{k+1} = r + r^2 + r^3 + \cdots + r^{n+1}$

and subtracting this from $S_n$ gives

$(1 - r) S_n = 1 - r^{n+1} \implies S_n = \dfrac{1 - r^{n+1}}{1 - r}$

As n → ∞, the exponential term will converge to 0, and the partial sums $S_n$ will converge to

$\displaystyle \lim_{n\to\infty} S_n = \dfrac1{1-r}$

Now, we're given

$a + ar + ar^2 + \cdots = 15 \implies 1 + r + r^2 + \cdots = \dfrac{15}a$

$a^2 + a^2r^2 + a^2r^4 + \cdots = 150 \implies 1 + r^2 + r^4 + \cdots = \dfrac{150}{a^2}$

We must have |r| < 1 since both sums converge, so

$\dfrac{15}a = \dfrac1{1-r}$

$\dfrac{150}{a^2} = \dfrac1{1-r^2}$

Solving for r by substitution, we have

$\dfrac{15}a = \dfrac1{1-r} \implies a = 15(1-r)$

$\dfrac{150}{225(1-r)^2} = \dfrac1{1-r^2}$

Recalling the difference of squares identity, we have

$\dfrac2{3(1-r)^2} = \dfrac1{(1-r)(1+r)}$

We've already confirmed r ≠ 1, so we can simplify this to

$\dfrac2{3(1-r)} = \dfrac1{1+r} \implies \dfrac{1-r}{1+r} = \dfrac23 \implies r = \dfrac15$

It follows that

$\dfrac a{1-r} = \dfrac a{1-\frac15} = 15 \implies a = 12$

and so the sum we want is

$ar^3 + ar^4 + ar^6 + \cdots = 15 - a - ar - ar^2 = \boxed{\dfrac3{25}}$

which doesn't appear to be either of the given answer choices. Are you sure there isn't a typo somewhere?

7 0

2 years ago

two planes traveling in opposite directions leave the airport at the same time. in 4 hours they are they are 2900 miles apart. i

marta [7]

I Got 650 miles per hour

6 0

3 years ago

Using the binomial theorem, expand the expression (4 + y) to the power of 4

Flauer [41]

Answer:

When raised to the power of 4, the binomial (4 + y) expands to:

$y^4 + 16y^3 + 96y^2 + 256y + 256$

Step-by-step explanation:

$(4 + y)^4 \\= (y^2 + 8y + 16)^2\\= y^4 + 8y^3 + 16y^2 + 8y^3 + 64y^2 + 128y + 16y^2 + 128y + 256\\= y^4 + 16y^3 + 96y^2 + 256y + 256$

8 0

3 years ago

Which trigonometric function has a range that does not include 0.4?

Montano1993 [528]

<h2>Hello!</h2>

The answer is: $y=cscx$

Domain and range of trigonometric functions are already calculated, so let's discard one by one in order to find the correct answer.

The range is where the function can exist in the vertical axis when we assign values to the variable.

First:

$y=cosx$ : Incorrect, it does include 0.4 since the cosine range goes from -1 to 1 (-1 ≤ y ≤ 1)

Second:

$y=cotx$ : Incorrect, it also does include 0.4 since the cotangent range goes from is all the real numbers.

Third:

$y=cscx$ : Correct, the cosecant function is all the real numbers without the numbers included between -1 and 1 (y≤-1 or y≥1).

Fourth:

$y=sinx$ : Incorrect, the sine function range is equal to the cosine function range (-1 ≤ y ≤ 1).

I attached a pic of the csc function graphic where you can verify the answer!

Have a nice day!

8 0

4 years ago