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What was Dimitri's mistake? He mixed up the coordinates of the ordered pair when Substituting it into the equations 7x+9y=-4 and 5x-2y=6

Sagot :

MrRoyalidn

Answer:

He made a mistake in his calculations when simplifying 5x - 2y

Step-by-step explanation:

Given

The coordinate pair

[tex](x,y) = (2,-2)[/tex]

The equations

[tex]7x + 9y = ?[/tex]

[tex]5x - 2y = ?[/tex]

Dimitri's Solution

[tex]Equation\ 1: 7x + 9y = -4.[/tex]

[tex]7(2) + 9 (-2) = -4.[/tex]

[tex]14 + (-18) = -4.[/tex]

[tex]-4 = -4.[/tex]

[tex]Equation\ 2: 5x -2y = 6.[/tex]

[tex]5(2) - 2 (-2) = 6.[/tex]

[tex]10 - 4 = 6.[/tex]

[tex]6 = 6.[/tex]

Required

Identify Dimitri’s mistake

In the first equation, Dimitri made no mistake.

However, he made a mistake when simplifying the second equation.

We have:

[tex]5x - 2y[/tex]

and

[tex](x,y) = (2,-2)[/tex]

Substitute [tex]x = 2[/tex] and [tex]y = -2[/tex]

So, we have:

[tex]5(2) -2(-2)[/tex]

Open bracket

[tex]10 +4[/tex]

Finally, we have:

[tex]14[/tex]

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