X + 3y = 7,

2x + 4y = 9

Which variable would be the most efficient to solve for?
x in the first equation
y in the first equation
x in the second equation
y in the second equation

see explanation

Step-by-step explanation:

Given the 2 equations

x + 3y = 7 → (1)

2x + 4y = 9 → (2)

Solving for y in the second equation.

Rearrange (1) expressing x in terms of y by subtracting 3y from both sides

x = 7 - 3y → (3)

Substitute x = 7 - 3y into (2)

2(7 - 3y) + 4y = 9 ← distribute and simplify left side

14 - 6y + 4y = 9

14 - 2y = 9 ( subtract 14 from both sides )

- 2y = - 5 ( divide both sides by - 2 )

y =

Substitute this value into (3) for corresponding value of x

x = 7 - 3( ) = 7 - = -

Solution is ( - , )

the direct variation says that:

then the equation is of the form is given by:

            where k is the constant variation.

from the given table:

consider any value of x and m(x)=y

x = 2 and m(x)=y = 3

substitute these value in [1]; we have;

divide both sides by 2 we get;

⇒

check:

put x = -1 and m(x) = -1.5

substitute in the equation:

-1.5 = -1.5                   true

therefore, the function m(x) represents a direct variation

graph of this function as shown below: