How do you determine whether a pair of numbers is a solution for an equation?

If you could identify the specifics steps I need to take to determine whether it is a solution or not would be appreciated! Thanks

i.e. x-4=0 Pairs of numbers as possible solutions (4,7) (3,4) (0,-4).



Hi,

For a pair of numbers like (4,7) the first number (here 4) is the x-value and the second number (here 7) is the y-value. To check to see if the pair of numbers is a solution to the equation you should deal with the two sides of the equation separately. They are usually called the left side and the right side.

Here is an example. Suppose that the equation is y + 1 = x + y - 2 and the possible solutions are (4,7), (3,4) and (0,3). Try the possible solutions one at a time.

(4,7): that is x = 4 and y = 7

left side
Since y = 7 the left side is y + 1 = 7 + 1 = 8.

right side
Since x = 4 and y = 7 the left side is x + y + 2 = 4 + 7 - 2 = 9.

Since the values of the left and right side are not equal, (4,7) is not a solution.


(3,4): that is x = 3 and y = 4

left side
Since y = 4 the left side is y + 1 = 4 + 1 = 5.

right side
Since x = 3 and y = 4 the left side is x + y + 2 = 3 + 4 - 2 = 5.

Since the values of the left and right side are equal, (3,4) is a solution.


(3,0): that is x = 3 and y = 0

left side
Since y = 0 the left side is y + 1 = 0 + 1 = 1.

right side
Since x = 3 and y = 0 the left side is x + y - 2 = 3 + 0 - 2 = 1.

Since the values of the left and right side are equal, (0,-4) is a solution.

Your equation x - 4 = 0 is particularly nice because the right side is always 0. Check the possible solutions (4,7), (3,4) and (0,-4) one at a time.

(4,7): that is x = 4 and y = 7

left side
Since x = 4 the left side is x - 4 = 4 - 4 = 0.

right side
The left side is 0.

Since the values of the left and right side are equal, (4,7) is a solution.


Are (3,4) and (0,-4) solutions? Cheers,
Penny

Go to Math Central