50 ! whoever is the first to answer out of two people gets marked as brainliest! determine best method to solve each system of equations. 19.) x + y = 2 20.) - x - 5y = 7 y = 2x - 1 x + y = 1 21.) 3x + y = 26 22.) 4x - 8y = 52 3x + 3y = 26 7x + 4y = 1

19 substitution

20 elimination

21 elimination

22 elimination

Step-by-step explanation:

19.) x + y = 2

y = 2x - 1

Substitution, since the second equation is already solved for y

x + (2x-1) =2

Combine like terms

3x-1 =2

Add 1 to each side

3x-1+1= 2+1

3x=3

Divide by 3

x=1

Now we need y

x+y =2

1+y= 2

Subtract 1

y=1

(1,1)

20.) - x - 5y = 7

x + y = 1

I will used elimination since  there is an x and a -x

- x - 5y = 7

x + y = 1

-4y = 8

Divide by -4

-4y/-4 = 8/-4

y = -2

x+y =1

x-2=1

Add 2 to each side

x-2+2=1+2

x=3

(3,-2)

21.) 3x + y = 26

3x + 3y = 26

I will use elimination by multiplying the second equation by -1

3x + y = 26

-3x - 3y = -26

   -2y = 0

Divide by -2

-2y/-2 = 0/-2

y =0

Now we need to find x

3x + 0 = 26

Divid by 3

3x/3  = 26/3

x = 26/3

(26/3 ,0)

22.) 4x - 8y = 52

7x + 4y = 1

I will use elimination by multiplying the second equation by 2

2( 7x + 4y = 1 )

14x +8y =2

The add this to the first equation to eliminate y

4x - 8y = 52

14x +8y =2

18x = 54

Divide by 18

18x/18 = 54/18

x=3

Now we need to find y

7x + 4y = 1

7(3) +4y = 1

21 +4y = 1

Subtract 21 from each side

21-21 +4y = 1-21

4y = -20

Divide by 4

4y/4 = -20/4

y=-5

(3,-5)

pi x^2

step-by-step explanation:

pi times x squared

the answer is 13/48

step-by-step explanation: