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If √ 13 − a √ 10 = √ 8 + √ 5 , Then a = - Mathematics

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प्रश्न

If \[\sqrt{13 - a\sqrt{10}} = \sqrt{8} + \sqrt{5}, \text { then a } =\]

विकल्प

  • −5

  • −6

  • −4

  • −2

MCQ

उत्तर

Given that:`sqrt(13- a sqrt10)= sqrt8 +sqrt5`

We need to find a

The given expression can be simplified by taking square on both sides 

`(sqrt(13- a sqrt10)^2)= (sqrt8 +sqrt5)^2`

`13-asqrt10 = (sqrt8)^2 +(sqrt5)^2 + 2xx sqrt8xx sqrt5`

                    `= 8+ 5 +2sqrt40`

The irrational terms on right side can be factorized such that it of the same form as left side terms. 

Hence,

`13 - asqrt10 = 13 +2 sqrt4 sqrt10`

` =13+2xx2xxsqrt10`

`= 13+4sqrt10.`

On comparing rational and irrational terms, we get `a=-4`.

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 3: Rationalisation - Exercise 3.4 [पृष्ठ १८]

APPEARS IN

आरडी शर्मा Mathematics [English] Class 9
अध्याय 3 Rationalisation
Exercise 3.4 | Q 25 | पृष्ठ १८

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