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Evaluate the expression (i) 4x^(3)+2x^...

Evaluate the expression
`(i) 4x^(3)+2x^(2)-8x+7` for `x=(1)/(2)(sqrt(3)+1)`
`(ii) 3x^(2)+4xy-3y^(2)` for `x=(sqrt(5)+sqrt(2))/(sqrt((5))-sqrt((2)))`, `y=(sqrt(5)-sqrt(2))/(sqrt((5))+sqrt((2)))`
`(iii) x^(2)+xy+y^(2)` for `x=(sqrt(3)-sqrt(2))/(sqrt((3))+sqrt((2)))` , `y=(sqrt(3)+sqrt(2))/(sqrt((3))-sqrt((2)))`.

Text Solution

Verified by Experts

The correct Answer is:
(i) 10
(ii)`(1)/(3)[12+56sqrt(10)]`
(iii) 99
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ML KHANNA-LOGARITHMS AND SURDS-Problem Set (4)
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  2. Which of the given numbers is greatest ? 6root3(5), root3(2),2root3(...

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  3. Evaluate the expression (i) 4x^(3)+2x^(2)-8x+7 for x=(1)/(2)(sqrt(3)...

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  4. If x = (2ab)/(b^2+1) then value of (sqrt(a+x)+sqrt(a-x))/(sqrt(a+x)-sq...

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  5. If x=(sqrt(a+2b)+sqrt(a-2b))/(sqrt(a+2b)-sqrt(a-2b)), then find the va...

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  6. Express as an equivalent fraction with rational denominator. (8sqrt(...

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  8. Express as an equivalent fraction with rational denominator. (sqrt(1...

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  9. Simplify ((sqrt3+sqrt5)(sqrt5+sqrt2))/(sqrt2+sqrt3+sqrt5)

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  11. Express as an equivalent fraction with rational denominator. (1)/(sq...

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  13. Express as an equivalent fraction with rational denominator. (i) (3+...

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  14. Express as an equivalent fraction with rational denominator. (sqrt(2...

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  15. Express as an equivalent fraction with rational denominator. ([sqrt(...

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  16. (12)/( 3+ sqrt(5 ) + 2sqrt(2)) is equal to

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  17. Prove the following identities. ((a+2)^(2)(a-3)+(a^(2)-4)sqrt(a^(2)-...

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  18. Prove the following identities. (n^(3)-3n+(n^(2)-1)sqrt(n^(2)-4)-2)/...

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  19. Express with rational denominator : (4)/(root3((9))-root3(3)+1)

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  20. Express with rational denominator : (sqrt(8)+root3(4))/(sqrt((8))-ro...

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