Math, asked by LUCKYPANDA, 11 months ago

5. In a class test, the sum of Shefali's marks in Mathematics and English is
2 marks more in Mathematics and 3 marks less in English, the producing
would have been 210. Find her marks in the two subjects.

Answers

Answered by Anonymous
9

SOLUTION :  

Let the marks in Maths be x.

Then, the marks in English will be 30 - x.

A.T.Q

(x + 2)(30 - x - 3) = 210

(x + 2)(27 - x) = 210

⇒ -x² + 25x + 54 = 210

⇒ x² - 25x + 156 = 0

⇒ x² - 12x - 13x + 156 = 0

[By middle term splitting]

⇒ x(x - 12) -13(x - 12) = 0

⇒ (x - 12) (x - 13) = 0

⇒ (x - 12) = 0 or  (x - 13) = 0

⇒ x = 12  or x = 13

Case 1 :  

If the marks in Maths are 12, then marks in English will be 30 - 12 = 18

Case 2:  

If the marks in Maths are 13, then marks in English will be 30 - 13 = 17

Hence, the marks in Maths are (12,13) and marks in English are (18,17)

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Answered by Anonymous
7
  • Let Shefali's marks in Mathematics = x
  • Then, Shefali's marks in in English = 30-x

Now, according to the question,

  • Marks in Mathematics = x+2
  • Marks in English = (30-x-3) = 27-x

Given,

(x + 2)(27 - x) = 210 \\

27x  -  {x}^{2}  + 54 - 2x = 210

25x -  {x}^{2}  + 54 = 210

 {x}^{2}  - 25x + 156 = 0

As,

  • D =   \frac{- b± \sqrt{ {b}^{2} - 4ac } }{2a}

 =  \frac{25 ± \sqrt{ {( - 25)}^{2} - 4 \times 156 } }{2 \times 1}

 =  \frac{25 ±  \sqrt{625 - 624} }{2}

 =  \frac{26}{2} \:  \:  \:  \:   and \:  \:  \:    \: \frac{24}{2}

 = 13 \:  \:  \:  \:   \:and \:  \:  \:  \:12

So,

Case 1

When the marks in Mathematics is 12.

Then, in English will be 30-12=18.

Case 2

When the marks in Mathematics is 13.

Then, in English will be 30-13=17.

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