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All right.
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So for number 71, we have 10x to the fourth minus 21 x to the third, minus 16x squared plus 23x minus 20, divided by 2x minus 5.
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So the first thing we want to look at is that 10x to the fourth and what it takes for 2x to go into that.
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So 2 goes into 10, 5 times, x goes into x to the 4th, x to the 3 times.
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I then take that 5x to the third multiply it by the 2x to get the 10x to the fourth, and then i do negative 5 times 5x to the third.
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That's going to get me negative 25x to the third.
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I then need to make this cancel by causing this to be subtraction, and this becomes positive.
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It is very important that you do both, change both signs here.
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So i then do 25x to the third, take away 21x the third gives me a positive 4.
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X to the third minus 16x squared.
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2x goes into 4x of the third 2x squared times...