Question

the sum of the reciprocal of rehmans ages(in years) 3 years ago and 5 years from now is 1/3 find his present age.
please tell me from which chapter the following question is and also its solution.

Answer 1

Answer:

7 years

Step-by-step explanation:

Let the present age of rehman be x.

Age  3 years ago = x -3 .

Age 5 years from now = x + 5.

given, Sum of reciprocal of these ages is 1/3.

=> 1/x -3 + 1/x +5 = 1/3

=> x + 5 + x -3 /(x+5)(x-3) = 1/3

=> 2x +2 / x²  +2x  - 15 = 1/3

=> 6x +6 = x² +2x - 15

=> x² - 4x - 21 = 0

=> x² - 7x + 3x - 21 = 0

=> x(x-7) + 3(x-7) = 0

=> (x-7)(x+3)= 0

=> x = 7 or -3.

Since age cannot be negative x = -3 can be discarded.

Thus the age of rehman = 7 yrs.

This would be belong to chapter "Quadratic equations"  Chapter 4, NCERT class 10th

Answer 2

Answer:

Please refer the attachment dear