How do you solve for r in #4(r+3)=t#?
2 Answers
r=t-12/4
Explanation:
4[r+3]=t
4r+12=t
4r=t-12
r=t-12/4
Explanation:
Why the shortcut method works:
Consider the following:
So it follows that
From this you can see that there is 4 lots of r and 4 lots of 3's
So when multiplying out the bracket we have the equivalent of
So
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Given:
This is the same as:
We are told that we need to solve for r. That means we must end up with only one r in the equation and that it is to be on the left hand side of the equals sign. Everything else is to be on the other side.
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Collect all the terms with r on the left of = and everything else on the right. So we need to move the 12 to the other side.
To remove 12 from the left we do the following
Subtract
But
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Any number multiplied by 1 does not change its value. We need r on its own. So we change the 4 into 1
Divide both sides by
This is the same as
But
But
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For add, move the term to the other side of the = and change the sign to subtract.
For subtract, move the term to the other side of the = and change the sign to add.
For multiply, move the term to the other side and divide by it.
For divide, move the term to the other side of the = and multiply by it.
Hope this helps in solving other question.