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For each of these, make y the subject a.) b - y = x    b.) 11 + 2y =7x    c.) y/3 =...

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jovid95 | Student, Undergraduate | eNoter

Posted March 11, 2012 at 6:15 AM via web

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For each of these, make y the subject

a.) b - y = x    b.) 11 + 2y =7x    c.) y/3 = 7x + 3

Hello I am strugling on these questions, I did a lesson on them last week and I understud them but now there in a different form and I'm confussed. can someone show me how to do these?

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mlsiasebs | College Teacher | (Level 1) Associate Educator

Posted March 11, 2012 at 6:25 AM (Answer #1)

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When we are trying to make y the subject, it just means that we are solving the equations for y.  In other words, we need to get y on the left by itself.

For the first one, b - y = x

First we want to move the b to the right side by subtracting b from both sides

- y = x - b

Now, we need to multiply both sides by -1 to get

y = - x + b

which leaves y as the subject.

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For the second one, 11 + 2y = 7x

subtract 11 from both sides

2y = 7x -11

divide both sides by 2

y = 7/2 * x - 11/2

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For the third one, y/3 = 7x + 3

we need to multiply both sides by 3 to cancel it out

y = 21x + 9

 

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