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3 years ago

4x-y=20 and -2x-2y=10

Mathematics

1 answer:

lara31 [8.8K]3 years ago

6 0

You can use Substitution to solve this problem:

4x-y=20

-y=-4x+20

y=4x-20

Now you have two equations, and you use the first one to substitute into the second one.

y=4x-20 and -2x-2y=10

-2x-2(4x-20)=10

-2x-8x+40=10

-10x+40=10

-10x=-30

-x=-3

x=3

Now that we have figured out what x is, we can substitute x in to one of the equations to figure out y.

4x-y=20 x=3

4(3)-y=20

12-y=20

-y=8

y=-8

So your answer would be x=3 and y=-8

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Now there is a door whose height is more than its width by 6 chi 8 cun. The distance between the [opposite] corners is 1 zhang.

Kaylis [27]

Answer:

height: 9 chi 6 cun
width: 2 chi 8 cun

Step-by-step explanation:

The factor-of-ten relationship between the different units means we can combine the numbers in decimal fashion. If 1 unit is 1 zhang, then 1 chi is 0.1 zhang and 1 cun is 0.01 zhang. Hence 6 chi 8 cun is 0.68 zhang.

Let x and y represent the width and height, respectively. In terms of zhang, we have ...

y - x = 0.68

x^2 +y^2 = 1^2

Substituting y = 0.68 +x into the second equation gives ...

x^2 + (x +0.68)^2 = 1

2x^2 +1.36x - 0.5376 = 0 . . . . . eliminate parentheses, subtract 1

Using the quadratic formula, we have ...

x = (-1.36 ±√(1.36^2 -4(2)(-0.5376)))/(2·2) = (-1.36 ±√6.1504)/4

x = 0.28 . . . . . the negative root is of no interest

y = 0.28 +0.68 = 0.96

In units of chi and cun, the dimensions are ...

height: 9 chi 6 cun

width: 2 chi 8 cun

6 0

3 years ago

Read 2 more answers

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Eva8 [605]

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5 0

3 years ago

Solve with steps 5^(x+3)=25^(x-2)

Taya2010 [7]

5^(x+3)=25^(x-2)

Apply the exponent rule ( 5 ^2 = 25, so remove the 5 and replace 25?with 2)

x + 3 = 2(x-2)

Simplify:

X + 3 = 2x -4

Add 4 to both sides:

X + 7 = 2x

Subtract x from both sides

X = 7

Answer: x = 7

6 0

2 years ago

What is the equation in point-slope form of a line that passes through the points (3, −5) and (−8, 4) ?

maxonik [38]

ANSWER

$y + 5= - \frac{9}{11} (x-3)$

or

$y - 4= - \frac{9}{11} (x + 8)$

EXPLANATION

We want to find the equation in point-slope form of a line that passes through the points (3, −5) and (−8, 4).

The point-slope form is given by;

$y-y_1=m(x-x_1)$

where

$m = \frac{4 - - 5}{ - 8 - 3} = \frac{4 + 5}{ - 11} = - \frac{9}{11}$

is the slope of the line.

If

$(x_1,y_1)=(3,-5)$

The point-slope form is

$y + 5= - \frac{9}{11} (x-3)$

On the other hand, if
$(x_1,y_1)=( - 8,4)$

Then the point-slope form is,

$y - 4= - \frac{9}{11} (x + 8)$

These two equations are the same when simplified.

4 0

3 years ago

If m<9 = 119, what is the sum of the measure of <11 and <6

Phantasy [73]

If this is a triangle the the measure of angles 11 and 6 could be any number between 1 and 60

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3 years ago