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3 years ago

Earl runs 75 meters in 30 seconds .How many meters does Earl run per second

Mathematics

1 answer:

belka [17]3 years ago

6 0

Answer:

2.5 meters per second

Step-by-step explanation:

75/30 = 2.5

I'd choose 25 because the person who wrote the answers probably forgot to add decimal points

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The sum of first three terms of a finite geometric series is -7/10 and their product is -1/125. [Hint: Use a/r, a, and ar to rep

Alchen [17]

Ooh, fun

geometric sequences can be represented as
$a_n=a(r)^{n-1}$
so the first 3 terms are
$a_1=a$
$a_2=a(r)$
$a_2=a(r)^2$

the sum is -7/10
$\frac{-7}{10}=a+ar+ar^2$
and their product is -1/125
$\frac{-1}{125}=(a)(ar)(ar^2)=a^3r^3=(ar)^3$

from the 2nd equation we can take the cube root of both sides to get
$\frac{-1}{5}=ar$
note that a=ar/r and ar²=(ar)r
so now rewrite 1st equation as
$\frac{-7}{10}=\frac{ar}{r}+ar+(ar)r$
subsituting -1/5 for ar
$\frac{-7}{10}=\frac{\frac{-1}{5}}{r}+\frac{-1}{5}+(\frac{-1}{5})r$
which simplifies to
$\frac{-7}{10}=\frac{-1}{5r}+\frac{-1}{5}+\frac{-r}{5}$
multiply both sides by 10r
-7r=-2-2r-2r²
add (2r²+2r+2) to both sides
2r²-5r+2=0
solve using quadratic formula
for $ax^2+bx+c=0$
$x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}$
so
for 2r²-5r+2=0
a=2
b=-5
c=2

$r=\frac{-(-5) \pm \sqrt{(-5)^2-4(2)(2)}}{2(2)}$
$r=\frac{5 \pm \sqrt{25-16}}{4}$
$r=\frac{5 \pm \sqrt{9}}{4}$
$r=\frac{5 \pm 3}{4}$
so
$r=\frac{5+3}{4}=\frac{8}{4}=2$ or $r=\frac{5-3}{4}=\frac{2}{4}=\frac{1}{2}$

use them to solve for the value of a
$\frac{-1}{5}=ar$
$\frac{-1}{5r}=a$
try for r=2 and 1/2
$a=\frac{-1}{10}$ or $a=\frac{-2}{5}$

test each
for a=-1/10 and r=2
a+ar+ar²= $\frac{-1}{10}+\frac{-2}{10}+\frac{-4}{10}=\frac{-7}{10}$
it works

for a=-2/5 and r=1/2
a+ar+ar²= $\frac{-2}{5}+\frac{-1}{5}+\frac{-1}{10}=\frac{-7}{10}$
it works

both have the same terms but one is simplified

the 3 numbers are $\frac{-2}{5}$ , $\frac{-1}{5}$ , and $\frac{-1}{10}$

6 0

3 years ago

6th grade RATIOS

dsp73

Answer:

i would say b

Step-by-step explanation: if they all slept 4 hours a night then all 9 would have a total of 36 and a night would be 1 so 36 to 1

6 0

3 years ago

Find the value of X?

daser333 [38]

Because we know the midpoint is in the middle, we know that both sides are equal.
So set both = to each other
4x - 1 = 3x + 3

add 1 to both sides

4x=3x+4

then subtract 3x from both sides and because there is always a 1 in front of x the answer would be

x=4

3 0

2 years ago

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Which of the following statements best describes the graph of 3x − 2y = 4?

tigry1 [53]

<span>B.) It is a straight line joining the points (0, −2), (2, 1), and (−2, −5).

[ It is because x- & y-coordinates are valid in this situation ]

Hope this helps!</span>

6 0

3 years ago

Read 2 more answers

How to solve this?can you help me i no sure

dangina [55]

To find the answer just substitute the values of P and Q into the equation and evaluate following order of operations

7 0

3 years ago

Earl runs 75 meters in 30 seconds .How many meters does Earl run per second​

Earl runs 75 meters in 30 seconds .How many meters does Earl run per second