What is the coefficient of x⁴ in the expansion of ( 1 + x)(1-x)^n

=(-1)^n (1-n)

Step-by-step explanation:

=coefficient of x^n in (1-x)^n + coefficient of x^n-1 in (1-x)^n

=(-1)^n ^nCn + (-1)^n-1 ^nCn -1

=(-1)^n (1-n)

4 packs of water and 7 packs of candy bars

step-by-step explanation:

35x4=140

140/20=7

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.