Question

$a {}^{n } - b {}^{n} = {?}$
please answer this question​

Answer 1

Answer:

12

The number of students answering at least r questions incorrectly is 2

n−r

Thus the number of students answering exactly r (0≤r≤n−1) question incorrectly is 2

n−r

−2

n−(r+1)

.

Also, the total number of wrong answers is =1(2

n−1

−2

n−2

)+2(2

n−2

−2

n−3

)+3(2

n−3

−2

n−4

)+....+(n−1)(2

1

−2

0

)+n2

0

=2

n−1

+2

n−2

+2

n−3

+....+2

0

=2

n

−1

⇒2

n

−1=4095⇒2

n

=4096⇒n=12

Answer 2

Answer:

a-b+b

Step-by-step explanation:

2ab+3ab

5ab

a+2a

2a