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Nana76 [90]
3 years ago
13

How to solve system of equations khan academy?

Mathematics
1 answer:
Tamiku [17]3 years ago
7 0
You can use the elimination method.

You can have y crossed out so you can solve for x and then have x crossed out to solve for y for instance:

X - y = 8
+
X +y =4

To have y gone we have to make it equal to y - y or in this case -y + +y
So
X - y = 8
+
X + y = 4

2x = 12
———-
2. 2

X=6

Now to find y we have x crossed out.

X-y=8
X+y=4

To have x crossed out we’d do x - x
So

X-y = 8
-
X+ y = 4

-2y = 4
————-
-2. -2

Y = -2

Since coordinates go like (x,y) the system of equations for this problem is (6, -2)
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Here is a table of values for y = f(x).
DanielleElmas [232]

the complete question in the attached figure

statements

case A) f(15)=8-----> is correct

for x=15

f(x)=8

case B) the domain of f(x) is the set {5,6,7,8,10,11,12,13}--> is not correct

because the domain of f(x) is the set {0,5,10,15,20,25,30,35,40}

case C) f(5)=6-----> is  correct

for x=5

f(x)=6

case D) the range for f(x) is all real numbers----> is not correct

because

the range of f(x) is the set {5,6,7,8,9,10,11,12,13}

the answer is

A and C

7 0
3 years ago
If PQRS is a rhombus,which statement must be true? Check all that apply.
Oxana [17]

Answer: A, B, C, D

Step-by-step explanation:

A. This is true because all rhombi are parallelograms, and diagonals of a parallelogram bisect each other.

B. This is true because the diagonals of a rhombus are perpendicular.

C. This is true because diagonals of a rhombus bisect the angles from which they are drawn,

D. This is true because all sides of a rhombus are congfruent.

E. This is not always true - all rhombi are parallelograms, and adjacent angles of a parallelogram are supplementary, but not always congruent.

F. This is not always true - diagonals of a rhombus are not always congruent.

8 0
2 years ago
Alexis bought a CD player. She does not remember the price, but she does know that the 5% sales tax came to $4.80. What was the
snow_lady [41]

Answer:

Price of CD player = $96

Step-by-step explanation:

Given:

Sales tax = 5%

Amount of sales tax = $4.80

Find:

Price of CD player

Computation:

Price of CD player = Amount of sales tax / Sales tax

Price of CD player = 4.8 / 5%

Price of CD player = $96

6 0
2 years ago
Please help! Thank you!
KIM [24]
The correct answer is:  [B]:  " (2, 5) ".
__________________________________________
Given:
__________________________________________
  -5x + y = -5 ;
  -4x + 2y = 2 .
___________________________________________
  Consider the first equation:
___________________________
-5x + y = -5 ;  ↔ y + (-5x) = -5 ;

↔ y - 5x = -5 ;  Add "5x" to each side of the equation; to isolate "y" on one side of the equation; and to solve in terms of "y".
_____________________________________________
   y - 5x + 5x = -5 + 5x  

   y = -5 + 5x ;  ↔ y = 5x - 5 ;
____________________________________________
 Now, take our second equation:
______________________________
     -4x + 2y = 2 ; and plug in "(5x - 5)" for "y" ;  and solve for "x" :
_____________________________________________________
         -4x + 2(5x - 5) = 2 ; 
______________________________________________________
Note, 2(5x - 5) = 2(5x) - 2(5)  = 10x - 10 ;
__________________________________________
So:   -4x + 10x - 10 = 2 ;

On the left-hand side of the equation, combine the "like terms" ;

-4x +10x = 6x ;  and rewrite:

6x - 10 = 2  ;

Now, add "10" to each side of the equation:

6x - 10 + 10 = 2 + 10 ;

to get:

           6x = 12 ;  Now, divide EACH side of the equation by "6" ; to isolate "x" on one side of the equation; and to solve for "x" ; 

           6x/6 = 12 / 6 ;
 
                 x = 2 ;
_________________________________
Now, take our first given equation; and plug our solved value for "x" ; which is "2" ; and solve for "y" ;
_____________________________________
-5x + y = -5  ;

-5(2) + y = -5 ;

-10 + y = -5 ;  ↔
                              y - 10 = -5  ;

Add "10" to each side of the equation; to isolate "y" on one side of the equation; and to solve for "y" ;
     
         y - 10 + 10 = -5 + 10 ;

                   y = 5 .
_____________________________
So, we have, x = 2 ; and y = 5 .
____________________________
Now, let us check our work by plugging in "2" for "x" and "5" for "y" in BOTH the original first and second equations:
______________________________
first equation: 

-5x + y = -5 ;

-5(2) + 5 =? -5?

-10 + 5 =? -5 ? YES!
______________________
second equation:

-4x + 2y = 2 ;

-4(2) + 2(5) =? 2 ?

-8 + 10 =? 2 ?  Yes!
_______________________________________________________
So, the answer is: 
___________________________________________________________
          x = 2 , y = 5 ; or, "(2, 5)" ;  which is: "Answer choice: [B] " .
___________________________________________________________



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