Question

which are thrwe ordered pairs that make the equation y=7-x true? A (0,7) (1.8), (3,10) B (0,7) (2,5),(-1,8) C (1,8) (2,5),(3,10)D (2,9),(4,11),(5,12)

Answer 1

In order to corroborate that the points belong to the equation, we must subtitute the points into the equation.

If we substitute the points from option A, we get

`\begin{gathered} 7=7-0 \\ 7=7 \end{gathered}`

for (1,8), we have

`\begin{gathered} 8=7-1 \\ 8=6\text{ !!!} \end{gathered}`

then, option A is false.

Now, if we substitute the points in option B, for point (2,5), we have

`\begin{gathered} 5=7-2 \\ 5=5 \end{gathered}`

which is correct. Now, for point (-1.8) we obtain

`\begin{gathered} 8=7-(-1) \\ 8=8 \end{gathered}`

Since all the points fulfil the equation, then option B is an answer.

Lets continue with option C and D.

If we substitute point (1,8) from option C, we have

`\begin{gathered} 8=7-1 \\ 8=6\text{ !!!} \end{gathered}`

then, option C is false.

If we substite point (4,11) from option D, we get

`\begin{gathered} 11=7-4 \\ 11=2\text{ !!!} \end{gathered}`

then, option D is false.

Therefore, the answer is option B.