How do you expand (1+2x)6 using Pascal’s Triangle?

1 Answer
Jan 17, 2016

Use the appropriate row of Pascal's triangle and a sequence of powers of 2 to find:

(1+2x)6=1+12x+60x2+160x3+240x4+192x5+64x6

Explanation:

Write out Pascal's triangle as far as the row which begins 1,6...

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This gives you the sequence of coefficients for (a+b)6:

1,6,15,20,15,6,1

Then we can account for the factor of 2 of the 2x term, by multiplying by a sequence of powers of 2:

1,2,4,8,16,32,64

to get:

1,12,60,160,240,192,64

Hence:

(1+2x)6=1+12x+60x2+160x3+240x4+192x5+64x6