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3 years ago

Substitution method x-7y=-9 -x+8y=10

Mathematics

1 answer:

max2010maxim [7]3 years ago

7 0

Answer:

x = -2, y=1

Step-by-step explanation:

x-7y=-9---------------------equation 1

-x+8y=10-------------------equation 2

From equation 1, make x the subject of formula

x=7y-9----------------------equation 3

substituting x=7y-9 in equation 2,

-(7y-9)+8y=10

Expanding bracket

-7y+9+8y=10

Collecting like terms

8y-7y=10-9

y=1

substituting y=1 in 3

x=7(1)-9

x=7-9

x=-2

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FinnZ [79.3K]

Answer:

c. 2,320miles

Step-by-step explanation:

29 divided by 1/4 = 116

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3 years ago

Find the area of a trapezoid with bases 14 cm and 18 cm and height 10 cm.

4vir4ik [10]

You should add the two bases and muliply them with the height and then divide with 2
(14+18)×10÷2=160

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4 years ago

there is 4/5 lb of sand in science supplies. if one scoop of sand weighs 1/20 of a lb how many scoops of sand can maria get from

tatuchka [14]

We want to divide whole sand into scoops, so we have to divide 4/5 by 1/20. Lets do this

$\frac{ \frac{4}{5} }{ \frac{1}{20} }$
We know that if we want to divide 2 fraction we can multiply first by inverse of second fraction instead of dividing.,so:
$\frac{ \frac{4}{5} }{ \frac{1}{20} }$
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5 0

3 years ago

Suppose that the height (in centimeters) of a candle is a linear function of the amount of time (in hours) it has been burning.

natka813 [3]

Suppose that the height (in centimeters) of a candle is a linear function of

the amount of time (in hours) it has been burning.

Let x be the amount of time in hours

Let y be the heoght of a candle in centimeters

The two points are then as (9,24.5) and (23,17.5).

$\mathrm{Find\:the\:line\:}\mathbf{y=mx+b}\mathrm{\:passing\:through\:}\left(9,\:24.5\right)\mathrm{,\:}\left(23,\:17.5\right)$

$\mathrm{Slope\:between\:two\:points}:\quad \mathrm{Slope}=\frac{y_2-y_1}{x_2-x_1}$

$\left(x_1,\:y_1\right)=\left(9,\:24.5\right),\:\left(x_2,\:y_2\right)=\left(23,\:17.5\right)$

$m=\frac{17.5-24.5}{23-9}$

$m=-0.5$

$\mathrm{Plug\:the\:slope\:}-0.5\mathrm{\:into\:}y=mx+b$

$y=\left(-0.5\right)x+b$

$\mathrm{Plug\:in\:}\left(9,\:24.5\right)\mathrm{:\:}\quad \:x=9,\:y=24.5$

$24.5=\left(-0.5\right)\cdot \:9+b$

$-4.5+b=24.5$

$b=29$

$\mathrm{Construct\:the\:line\:equation\:}\mathbf{y=mx+b}\mathrm{\:where\:}\mathbf{m}=-0.5\mathrm{\:and\:}\mathbf{b}=29$

$y=-0.5x+29$

Now plug in x=21, we get

$y=-0.5*21+29=18.5$

Thus the height of the candle after 21 hours is 18.5 centimeters.

7 0

3 years ago

(-3) + 8 – 7x7<br> I need help with this on

nika2105 [10]

Answer: -44

Step-by-step explanation: PEMDAS(Parenthesis; Exponent; Multiply; Divide; Add; Subtract)

First you multiply the seven with the other seven to get 49. The problem will look like this: (-3) + 8 - 49. Now just add the -3 and 8. You'd get 5.

Now the problem looks like this: 5 - 49. And you then get -44.

3 0

3 years ago