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3 years ago

Can someone please help me just give me what x is..

Mathematics

2 answers:

Reptile [31]3 years ago

8 0

Answer:

Step-by-step explanation:

Anastasy [175]3 years ago

3 0

95 degrees hope I helped

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A school bus has 25 seats, with 5 rows of 5 seats. 15 students from the first grade and 5 students from the second grade travel

rusak2 [61]

Number of ways the second grade students can sit on the first row is 5! = 5P5
Number of ways 15 first grade students can sit in the remaining 20 seats is 20P15

Therefore, required number of ways is 5P5 * 20P15. (option B)

6 0

3 years ago

Read 2 more answers

<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

3 years ago

On a science quiz with 45

Mariulka [41]

I think you should multiply 5x4=20.

7 0

3 years ago

Read 2 more answers

A 20 foot lamp post casts a shadow that is 28 feet long. Standing next to the lamp post is a 6 foot tall man. About how long is

motikmotik

It looks like the shadow for the lamp only went up 8 feet so I assuming it would go up 8 feet as well for the guy

8 0

3 years ago

Can Someone help me solve this?I was Never told how to do this.Thankssssss.

guapka [62]

Total students = 13 + 9 + 3 = 25

ballgame = 9/25 = 0.36 = 36%

answer
B. 36%

4 0

3 years ago

Can someone please help me just give me what x is..​

Can someone please help me just give me what x is..