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3 years ago

10

If you multiply a number by 3 and then subtract 5,you will get 40.what is the number. (someone check this plzz to mach sure in r

ight) two step equation word problem

2 answers:

photoshop1234 [79]3 years ago

4 0

x*3-5=40

x*3-5+5=40+5

x*3=45

x*3/3=45/3

x=15

Therefore, the number is 15.

liberstina [14]3 years ago

4 0

It would be 15.

3 x 15 = 45

45 - 5 = 40

Therefore, 15 would be correct.

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this is the answer: 28

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Step-by-step explanation:

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what is the volume of a right cylinder which has a base radius of 14 inches and a height of 2 inches?

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The answer is 28 for the volume

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The mean of the following data values is 32. <br> 19, 23, 35, 41, 42<br> A. True <br> B. False

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Step-by-step explanation:

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3 years ago

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

HELP ILL AWARD BRAINLIEST

inna [77]

Answer:

Think about it

Step-by-step explanation:

If you made $20 in 2 hrs you made $10 per hour

To find out how much you make per certain number of hrs multiply $10 by the number of hours

The equation is y = 10x + 0 <-- this is also answer to number 4

10x is the constant of proportionality I think.

5 0

4 years ago

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