Evaluate the expression: 8r + 3n when r = 4 and n = 5

47

Step-by-step explanation:

replace r by 4 and n by 5

8(4)+3(5) = 47

47

Step-by-step explanation:

We have the expression and are asked to add them. We also know the meaning of the variables.

8r + 3n

We know that r = 4 and n = 5. So we need to substitute :

8(4) + 3(5)

32 + 15

47

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: