Systems of equation questions attached below

Q 19) x = 4; y = 8.

Q 20) x = 0 ; y = 0.

Q 21) x = -1; y = -5.

Step-by-step explanation:

Q 19)

y = 3x - 4 (Equation 1)

x - 4y = -28 (Equation 2)

Put Equation 2 in Equation 1:

x - 4(3x - 4) = -28.

x - 12x + 16 = -28

-11x = -44.

x = -44/-11.

x = 4.

Put x = 4 in Equation 1:

y = 3(4) - 4.

y = 12 - 4.

y = 8.

Q 20)

2x - 3y = 13x - 4y (Equation 1)

-3x - 2y = 0 (Equation 2).

From Equation 2:

-2y = 3x.

y = -3x/2 (Equation 3).

Put Equation 3 in Equation 1:

2x - 3(-3x/2) = 13x - 4(-3x/2).

2x + 4.5x = 13x + 6x.

12.5x = 0.

x = 0.

Put x = 0 in Equation 3:

y = 0.

Q 21)

y = 4x - 1 (Equation 1).

y = -2x - 7 (Equation 2).

Since y = y, therefore:

4x - 1 = -2x - 7.

6x = -6.

x = -1.

Put x = -1 in Equation 1:

y = 4(-1) - 1.

y = -4 - 1.

y = -5.

In short:

Q 19) x = 4; y = 8!!!

Q 20) x = 0 ; y = 0!!!

Q 21) x = -1; y = -5!!!

Question 1:

For this case we have we have the following system of equations:

We substitute the first equation in the second one:

We look for the value of "y":

Finally, the solution of the system is:

Question 2:

For this case we have we have the following system of equations:

We manipulate the first equation:

We substitute in the second equation:

We look for the value of "y":

Finally, the solution of the system is:

Question 3:

For this case we have we have the following system of equations:

Equating the equations:

We look for the value of "y":

Finally, the solution of the system is:

whole numbers.

step-by-step explanation:

we are given the average monthly rainfall (in millimeters) model r(m) for the years 1900-2009 as a function of the month number m.

as we can see m is taken for the number of months for years 1900-2009.

we know that number of months can't be a negative number or decimal number or a fraction.

so, the number of months could be only positive whole numbers.

therefore, whole numbers is more appropriate for the domain of r.

5

step-by-step explanation: