Question

Complete the ordered pairs so they are solutions of the equation-2x-5y=30(? ,0)(0,?)(?, -2)

Answer 1

An ordered pair (a,b) is a solution of an equation when substituting a in place of x results in y=b. In the same way, if we substitute b in pace of y then the result must be x=a. So let's take each ordered pair and substitute the non missing value in place of the corresponding variable.

First we have (?,0) which means that we must take y=0 in the equation:

`\begin{gathered} -2x-5y=30 \\ -2x-5\cdot0=30 \\ -2x=30 \\ x=(30)/(-2) \\ x=-15 \end{gathered}`

This means that the first ordered pair is (-15,0).

Then we have (0,?) so:

`\begin{gathered} -2x-5y=30 \\ -2\cdot0-5y=30 \\ -5y=30 \\ y=(30)/(-5)=-6 \end{gathered}`

So the second ordered pair is (0,-6).

The third one is (?,-2):

`\begin{gathered} -2x-5y=30 \\ -2x-5\cdot(-2)=30 \\ -2x+10=30 \\ -2x=30-10=20 \\ x=(20)/(-2) \\ x=-10 \end{gathered}`

Then the third ordered pair is (-10,-2).