Math, asked by saniyamalik29032005, 7 months ago

Question- Write the quadratic equation for the following:“The age of Ruchi is twice the age of Monika. The

product of their ages will be 160 after four years. Find their present ages.”​

Answers

Answered by SillySam
42

Let the age of Monika be x years.

A/Q , Ruchi is twice the age of Monika .

\therefore Ruchi's age = 2x .

After 4 years,

  • Monika's age = x +4
  • Ruchi's age = 2x + 4

A/Q , product of their ages after 4 years is 160 .

\therefore (x+4) (2x + 4) = 160

→ x ( 2x + 4) + 4(2x + 4) = 160

→ 2x² + 4x + 8x + 16 = 160

→ 2x² + 12x + 16 = 160

Dividing the equation by 2 :

→ x² + 6x + 8 = 80

Hence the required quadratic equation is :

\boxed{\tt x^2 + 6x + 8 = 80}

Solving the equation :

x² + 6x + 8 = 80

→ x² + 6x +8 - 80 = 0

→ x² + 6x - 72 = 0

→ x² + ( 12 - 6) x -72 = 0

→ x² + 12x - 6 x - 72 = 0

→ x( x +12) - 6 (x + 12) = 0

→ (x-6) (x +12) = 0

x -6 = 0

→ x = 6

x +12 = 0

→ x = -12

Since age can't be negetive , ignoring the negetive value and taking x as 6 .

  • Monika's present age = 6 years
  • Ruchi's present age = 2× 6 = 12 years
Answered by MoonGurl01
7

ANSWER:

According to Problem:

Let the age of Monika be x years.

and, Ruchi's age will be 2x years.

Now,

Monika's age after 4 years = x + 4

And Ruchi's age after 4 years = 2x + 4

ATQ,

Product of their ages is 160 after 4 years.

=  (x + 4) (2x + 4) = 160

=  x(2x + 4) + 4(2x + 4) = 160

=  2 {x}^{2} + 4x+ 8x + 16 = 160

=  2 {x}^{2} + 12x + 16 = 160

Divide this quadratic equation by 2

 {x}^{2} + 6x + 8 = 80

By solving this equation:

=  {x}^{2} + 6x + 8 = 80

=  {x}^{2} + 6x + 8 - 80 = 0

=  {x}^{2} + 6x - 72 = 0

=  {x}^{2} + (12 - 6)x - 72 = 0

=  {x}^{2} + 12x - 6x - 72 = 0

=  x(x + 12) - 6(x + 12) = 0

=  (x - 6)(x + 12) = 0

=  (x - 6) = 0 \: or \: (x + 12) = 0

=  x = 6 \: or \: x = - 12

Note: As age cannot be negative, ignore the negative value and take x as 6.

Hence,

Monika's present age = x = 6 years.

Ruchi's present age = 2x = 2 × 6 = 12 years.

___________________________

Answered By : MoonGurl01

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