Question:
In the expansion \({\left( {3x – y} \right)^7}\), the term containing \({x^4}{y^3}\) is:
Reference explanation:
Correct answer: A
The general term in the above expansion is
\({T_{k + 1}} = C_7^k{.3^{7 – k}}{x^{7 – k}}. {\left( { – 1} \right)^k}. { y^k}\)
Ask the problem to occur when k = 3 .
Then the coefficient of the term containing \({x^4}.{y^3}\) is:
\( – C_7^3{.3^4}. {x^4}. {y^3} = – 2835. {x^4}.y\)
ADSENSE
=======================
MonToan.com shares with you the practice of multiple-choice tests according to the lesson of MATH 10. Multiple-choice questions with detailed answers help you compare and refer to assess your ability. I wish you all the best and success in your studies.
