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If a+b=10 and a^2+b^2=58 , find the valu...

If `a+b=10` and `a^2+b^2=58` , find the value of `a^3+b^3`

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Verified by Experts

Given
`a+b=10`
we know
`(a+b)^2=a^2+b^2+2ab`
`10^2=58+2ab`
`2ab=100−58=42`
`ab=21`
`(a+b)^3=a^3+b^3+3ab(a+b)`
`10^3=a^3+b^3+3×21×10`
`a^3+b^3=1000−630=370`
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RD SHARMA-ALGEBRAIC IDENTITIES-All Questions
  1. If x-1/x=3, find the value of x^3-1/(x^3)

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  2. If 2x+3y=13 and x y=6, find the value of 8x^3+27 y^3

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  3. If a+b=10 and a^2+b^2=58 , find the value of a^3+b^3

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  4. If x+1/x=7, find the value of x^3+1/(x^3)

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  5. Simplify each of the following expressions: (i) (x+y+z)^2+(x+y/2+z/3)...

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  6. Simplify each of the following: (4x+2y)^2+(4x-2y)^2 (4x+2y)^3-(4x-...

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  7. If x+y=12 and x y=27 , find the value of x^3+y^3

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  8. Prove that: 2a^2+2b^2+2c^2-2a b-2b c-2c a=[(a-b)^2+(b-c)^2+(c-a)^2]

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  9. Expand each of the following (i) (3x+4y)^2 (ii) (3x-4y)^2

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  10. Expand each of the following (i)(sqrt(2)x-3y)^2 (ii) (2x-1/(3x))^2

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  11. Expand each of the following (i)(x/2-y/3)^2 (ii) (x+5)(x-3)

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  12. Find the products: (i)(2x+3y)\ (2x-3y)

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  13. Find the products: (x-1/x)\ (x+1/x)(x^2+1/(x^2))\ (x^4+1/(x^4))

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  14. Find the products: (i) (2x+y)(2x-y)(4x^2+y^2)

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  15. Evaluate each of the following by using identities: (i)103 xx 97

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  16. Evaluate each of the following by using identities: (i)(0. 99)^2 (...

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  17. Evaluate each of the following by using identities: (i)0. 54 xx 0. 5...

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  18. Evaluate each of the following by using identities: (i)95 xx 96 (...

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  19. If x+(1)/(x)=6, find : x^2+ (1)/(x^2)

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  20. If x+1/x=6, find : x^4+1/(x^4)

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