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2 years ago

Plz i need help answer all plz for 30 points

Mathematics

1 answer:

yan [13]2 years ago

8 0

Step-by-step explanation:

16. Less than

18. 3.79L

19. I think 324 inches, but I am european.

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brilliants [131]

Answer:

(a) x=2, y=-1

(b) x=2, y=2

(c) $\displaystyle x=\frac{5}{2}, y=\frac{5}{4}$

(d) x=-2, y=-7

Step-by-step explanation:

Cramer's Rule

It's a predetermined sequence of steps to solve a system of equations. It's a preferred technique to be implemented in automatic digital solutions because it's easy to structure and generalize.

It uses the concept of determinants, as explained below. Suppose we have a 2x2 system of equations like:

$\displaystyle \left \{ {{ax+by=p} \atop {cx+dy=q}} \right.$

We call the determinant of the system

$\Delta=\begin{vmatrix}a &b \\c &d \end{vmatrix}$

We also define:

$\Delta_x=\begin{vmatrix}p &b \\q &d \end{vmatrix}$

And

$\Delta_y=\begin{vmatrix}a &p \\c &q \end{vmatrix}$

The solution for x and y is

$\displaystyle x=\frac{\Delta_x}{\Delta}$

$\displaystyle y=\frac{\Delta_y}{\Delta}$

(a) The system to solve is

$\displaystyle \left \{ {{x+y=1} \atop {x-2y=4}} \right.$

Calculating:

$\Delta=\begin{vmatrix}1 &1 \\1 &-2 \end{vmatrix}=-2-1=-3$

$\Delta_x=\begin{vmatrix}1 &1 \\4 &-2 \end{vmatrix}=-2-4=-6$

$\Delta_y=\begin{vmatrix}1 &1 \\1 &4 \end{vmatrix}=4-3=3$

$\displaystyle x=\frac{\Delta_x}{\Delta}=\frac{-6}{-3}=2$

$\displaystyle y=\frac{\Delta_y}{\Delta}=\frac{3}{-3}=-1$

The solution is x=2, y=-1

(b) The system to solve is

$\displaystyle \left \{ {{4x-y=6} \atop {x-y=0}} \right.$

Calculating:

$\Delta=\begin{vmatrix}4 &-1 \\1 &-1 \end{vmatrix}=-4+1=-3$

$\Delta_x=\begin{vmatrix}6 &-1 \\0 &-1 \end{vmatrix}=-6-0=-6$

$\Delta_y=\begin{vmatrix}4 &6 \\1 &0 \end{vmatrix}=0-6=-6$

$\displaystyle x=\frac{\Delta_x}{\Delta}=\frac{-6}{-3}=2$

$\displaystyle y=\frac{\Delta_y}{\Delta}=\frac{-6}{-3}=2$

The solution is x=2, y=2

$\displaystyle \left \{ {{-x+2y=0} \atop {x+2y=5}} \right.$

Calculating:

$\Delta=\begin{vmatrix}-1 &2 \\1 &2 \end{vmatrix}=-2-2=-4$

$\Delta_x=\begin{vmatrix}0 &2 \\5 &2 \end{vmatrix}=0-10=-10$

$\Delta_y=\begin{vmatrix}-1 &0 \\1 &5 \end{vmatrix}=-5-0=-5$

$\displaystyle x=\frac{\Delta_x}{\Delta}=\frac{-10}{-4}=\frac{5}{2}$

$\displaystyle y=\frac{\Delta_y}{\Delta}=\frac{-5}{-4}=\frac{5}{4}$

The solution is

$\displaystyle x=\frac{5}{2}, y=\frac{5}{4}$

(d) The system to solve is

$\displaystyle \left \{ {{6x-y=-5} \atop {4x-2y=6}} \right.$

Calculating:

$\Delta=\begin{vmatrix}6 &-1 \\4 &-2 \end{vmatrix}=-12+4=-8$

$\Delta_x=\begin{vmatrix}-5 &-1 \\6 &-2 \end{vmatrix}=10+6=16$

$\Delta_y=\begin{vmatrix}6 &-5 \\4 &6 \end{vmatrix}=36+20=56$

$\displaystyle x=\frac{\Delta_x}{\Delta}=\frac{16}{-8}=-2$

$\displaystyle y=\frac{\Delta_y}{\Delta}=\frac{56}{-8}=-7$

The solution is x=-2, y=-7

4 0

3 years ago

1. 1 +2r = 2. 12 = 18 - d 3. 5b + 10 = 30

seropon [69]

Answer:

1. r=anything

2. d=6

3. b=4

Step-by-step explanation:

6 0

2 years ago

Read 2 more answers

Jacob leaves his summer cottage and drives home. After

krok68 [10]

Answer:

A linear relationship can be written as:

y = a*x + b

Where a is the slope and b is the y-intercept.

If this line passes through the points (a, b) and (c, d) then the slope can be written as:

a = (a - c)/(b - d)

Here y will represent the distance between Jacob and his house, and the variable x represents the time that he has ben driving.

In this case, we know that after driving for 5 hours, he is 112km from home.

Then we can write this point as (5h, 112km)

We also know that after 7 hours he is 15km from home.

Then we can write this point as (7h, 15km)

Then the slope of this function will be:

a = (15km - 112km)/(7h - 5h) = -48.5 km/h

Then the equation is:

y = -(48.5 km/h)*x + b

To find the value of b, we can replace the values of one of the points, for example in the point (7h, 15km)

This means that we need to replace x by 12h, and y by 15km, then we get:

15km = -( 48.5 km/h)*7h + b

15km + ( 48.5 km/h)*7h = b = 354.5 km

then the equation will be:

y = (-48.5 km/h)*x + 354.5 km

Now we want to answer: How long had Jacob been driving when he was 209 km from home?

Then we need to only replace y by 209km, and solve for x:

209km = (-48.5 km/h)*x + 354.5 km

209km - 354.5 km = (-48.5 km/h)*x

-145.5km = (-48.5 km/h)*x

-145.5km/( -48.5 km/h) = x = 3h

So he is 209km away from his home after driving for 3 hours.

6 0

3 years ago

How many times will the digit "3" appear if we write all whole numbers from 1-9999?

Marysya12 [62]

Answer:

4000

Step-by-step explanation:

from 1 - 1000 = 300

1's = 100

10's = 100

100's = 100

1000's = 0

300 * 10 = 3000

then add in all the 3000's (ie 3001,3002, etc ) that adds one more thousand

3000 + 1000 = 4000

5 0

3 years ago

Write the standard form of the equation of the line through the pair of points (6,3) and (-7,7)

timofeeve [1]

Step-by-step explanation:

steps are in the picture above.

<h3>Note:if you need to ask any question please let me know.</h3>

3 0

3 years ago