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3 years ago

The perimeter of a rectangle is 150cm. The length is 15cm greater than the width. Find the dimensions

1 answer:

7 0

150/4 = 37.5cm. You divide by four because there are four sides on a rectangle. But 37.5 is the cm of a square. Since it says one of the sides is 15cm greater, you subtract 37.5 - 15 = 27.5cm on 2 of the width. While the other 2 lengths are greater than the width by 15 cm, so you add 15 to 37.5 which gives you 52.5cm. So the 2 width are 27.5cm and the length is 52.5cm.

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Select each pair of functions that are inverses of each other

svlad2 [7]

Answer:

The first two choices only: A and B.

Step-by-step explanation:

The inverses are the ones with one relation having point (x,y) and the other relation having point (y,x). This most obvious when looking at points on a table or a list of points.

So the first pair are inverses because per point (x,y) on the first list you have (y,x) on the second list.

Examples:

1st list contains (-5,-9) while second list contains (-9,-5).

1st list contains (3,7) while the second list contains (7,3).

As long as (a,b) is in the first list and (b,a) is in the second or vice versa, then the pair of relations are inverses. So the first choice contains inverses.

Now lets talk about the pair of functions given in function notation.

Let's start with the first.

y=x+7

Extend the first idea more. Just swap x and y and then see after solving for y if what it equals is what g equals then f and g are inverses in the second choice.

x=y+7

Subtract 7 on both sides:

x-7=y

y=x-7

This is what g equals so the second choice is an answer.

The last choice does not contain a pair of inverses. Example: (2,3) is in the first list but (3,2) is not in the second.

6 0

3 years ago

Read 2 more answers

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

SISTEMA DE ECUACIONES

Zina [86]

Step-by-step explanation:

5 0

3 years ago

A neon light flashes five times every 10 seconds. Show that the light flashes 43 200 times in one day.

11Alexandr11 [23.1K]

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds