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Mathematics

Is the following situation possible? If so, determine their present ages. The sum of the ages of two friends is 20 years. Four years ago, the product of their ages in years was 48.

Quadratic Equations

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Answer

Let age of first friend be x years, so age of other friend is (20 - x) years.

Four years ago,

Age of first friend = (x - 4) years and age of second friend = (20 - x - 4) = (16 - x) years.

Given,

Product of their ages in years was 48.

⇒ (x - 4)(16 - x) = 48

⇒ 16x - x2 - 64 + 4x = 48

⇒ 20x - x2 - 64 = 48

⇒ x2 - 20x + 64 + 48 = 0

⇒ x2 - 20x + 112 = 0

Comparing x2 - 20x + 112 = 0 with ax2 + bx + c = 0, we get :

a = 1, b = -20 and c = 112.

Substituting value in b2 - 4ac, we get :

⇒ (-20)2 - 4 × 1 × 112

⇒ 400 - 448

⇒ -48.

Since, b2 - 4ac < 0.

∴ Roots are imaginary.

Hence, the above situation is not possible.

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