SOLUTION: How do you: Find the coefficient of x^4 in the binomial expansion of (5+2x)^7 (with steps please) Thanks

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Question 935353: How do you:
Find the coefficient of x^4 in the binomial expansion of (5+2x)^7
(with steps please)
Thanks
Found 2 solutions by oscargut, stanbon:
Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!
Hi, the answer is: 70,000
If you need more help or details you can contact me at:
mthman@gmail.com
Thanks

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
How do you:
Find the coefficient of x^4 in the binomial expansion of (5+2x)^7 = (2x+5)^7
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x^4 appears in the 4th term
Form of the 4th term:: 7C4(2x)^4*5^3
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Coefficient:: 7C4 = 35
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Expansion of 1st term:: (2x)^4 = 16x^4
Expansion of 2nd term:: (5)^3 = 125
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4th term:: 35*16x^4*125 = 70,000x^4
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Cheers,
Stan H.