You can put this solution on YOUR website! write the first three terms of the expansion (a-b)^6
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Use Pascal's triangle
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1 6th power
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Notice that each element in the triangle is the sum of 2 above it, so you can fill it in quickly for "small" exponents. I wouldn't do it for an exponent of 50.
Since it's a-b, the signs alternate.
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The exponents of a decrease while b's increase.