Question

solve 11 and 12 plss....

Answer 1

Answer:

Step-by-step explanation

1.)x² + 1/x² + 1

= x² + 1/ x² + 1 + 1 - 1 ..............( added +1 and-1)

=x² + 1/x² + 2 - 1

=(x + 1/x)² -1 ............. ( a² + b² + 2ab = (a+b)²)

= (x + 1/x)(1 + 1/x) - 1 (x)(1/x)

= (x)(x+1/x)

2.)

the number is 21y5

to find y

therefore,

it is divisible by 9

so, the sum of the digit is divisible by 9.

this means that

2 + 1 + y + 5 = 9,18,27,36.........( all the number divisible by 9)

if we take the number 9, then

8 + y = 9

y = 1

if we take 18

we will get  y = 10.

but y is a single digit number

so,

y=1

bye

hope you like it

Answer 2

Please see the attachment