Question

( 2 ) The sum of Ketu's present age and her age after 10 years is 42 years. Find her present age.set up equation​

Answer 1

Let their present ages be x and 20−x yrs respectively.

Four years ago, their ages would be (x-4) and (16-x) yrs respectively.

(x−4)(16−x)=48

16x−x

2

−64+4x=48

x

2

−20x+112=0

b

2

−4ac=−48

Since the discriminant <0, the roots would be imaginary.

Hence, such a situation is not possible.

Answer 2

Given: Sum of Ketu's present age and her age after 10 years = 42

To find: Her present age

Let: Ketu's present age = X years

Solution: According to the given question and assumption made,

Ketu's present age + her age after 10 years = 42 years

If her present age is X years, her age after 10 years would be X + 10

⇒ X + (X + 10) = 42            (Required equation)

⇒ X + X + 10 = 42

⇒ 2X + 10 = 42

⇒ 2X = 42 - 10 = 32

⇒ X = 32/2 = 16

Hence, Ketu's present age is 16 years.