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If (a + (1)/(a)) ^(2) = 3, then the valu...

If `(a + (1)/(a)) ^(2) = 3,` then the value of `a ^(30) + a ^(24) + a ^(18) + a ^(12) + a ^(6) + 1 ` is:

A

`-1`

B

1

C

27

D

0

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equation \((a + \frac{1}{a})^2 = 3\) and find the value of \(a^{30} + a^{24} + a^{18} + a^{12} + a^{6} + 1\), we can follow these steps: ### Step 1: Simplify the given equation Starting with the equation: \[ (a + \frac{1}{a})^2 = 3 \] Taking the square root of both sides, we get: \[ a + \frac{1}{a} = \sqrt{3} \quad \text{or} \quad a + \frac{1}{a} = -\sqrt{3} \] ### Step 2: Cube both sides We will use the positive root for simplicity: \[ a + \frac{1}{a} = \sqrt{3} \] Now, we cube both sides: \[ (a + \frac{1}{a})^3 = (\sqrt{3})^3 \] Using the identity \( (x + y)^3 = x^3 + y^3 + 3xy(x + y) \), we have: \[ a^3 + \frac{1}{a^3} + 3(a)(\frac{1}{a})(a + \frac{1}{a}) = 3\sqrt{3} \] This simplifies to: \[ a^3 + \frac{1}{a^3} + 3(a + \frac{1}{a}) = 3\sqrt{3} \] Substituting \(a + \frac{1}{a} = \sqrt{3}\): \[ a^3 + \frac{1}{a^3} + 3\sqrt{3} = 3\sqrt{3} \] Thus, we find: \[ a^3 + \frac{1}{a^3} = 0 \] ### Step 3: Relate \(a^6\) to the equation From \(a^3 + \frac{1}{a^3} = 0\), we can deduce: \[ a^3 = -\frac{1}{a^3} \] Multiplying both sides by \(a^3\): \[ a^6 + 1 = 0 \implies a^6 = -1 \] ### Step 4: Substitute \(a^6\) into the expression Now we need to evaluate: \[ a^{30} + a^{24} + a^{18} + a^{12} + a^{6} + 1 \] We can express each term in terms of \(a^6\): \[ a^{30} = (a^6)^5 = (-1)^5 = -1 \] \[ a^{24} = (a^6)^4 = (-1)^4 = 1 \] \[ a^{18} = (a^6)^3 = (-1)^3 = -1 \] \[ a^{12} = (a^6)^2 = (-1)^2 = 1 \] \[ a^{6} = -1 \] Now substituting these values into the expression: \[ -1 + 1 - 1 + 1 - 1 + 1 \] ### Step 5: Simplify the expression Now we can simplify: \[ (-1 + 1) + (-1 + 1) + (-1 + 1) = 0 + 0 + 0 = 0 \] ### Final Answer Thus, the value of \(a^{30} + a^{24} + a^{18} + a^{12} + a^{6} + 1\) is: \[ \boxed{0} \]
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MOTHERS-ALGEBRA -MULTIPLE CHOICE QUESTION
  1. If (a + (1)/(a)) ^(2) = 3, then the value of a ^(30) + a ^(24) + a ^(1...

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  2. If (5 sqrt5 x^3-3 sqrt3 y^3) div (sqrt5x- sqrt3y)=(Ax^2+By^2+Cxy), the...

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  3. If x+y+z=19, x^2+y^2+z^2=133 and xz=y^2, then the difference between z...

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  4. If x^(4) + x^(-4) = 194 , x gt 0 then the value of ( x - 2) ^(2) i...

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  5. If 16x^2+9y^2 +4z^2= 24(x-y+z)-61, then the value of (xy + 2z) is : ...

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  6. If x + y + z = 19, xy + yz + zx = 114, then the value of sqrt(x^3+y^3+...

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  7. If [8(x+y)^3- 27(x-y)^3] div (5y-x) = Ax^2+Cy^2+Bxy, then the value of...

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  8. If a^(2) + b^(2) + 64c^(2) + 16c + 3 = 2(a+b), then the value of 4a^(7...

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  9. If x + y = 1 and xy(xy - 2) = 12, then the value of x^4+y^4 is: यदि ...

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  10. If (27x^3-343y^3) div (3x-7y)=Ax^2+By^2 +7Cyx, then the value of (4A -...

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  11. If a^2+b^2+c^2=21, and a + b + c = 7, then (ab + bc + ca) is equal to ...

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  12. If ab + bc + ca = 8 and a^2+b^2+c^2=20, then a possible value of 1/2 (...

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  13. If (8x^3-27y^3)div (2x-3y)= (Ax^2+Bxy+Cy^2), then the valueof (2A + B ...

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  14. If x = a + (1)/(a) and y = a - (1)/(a) then sqrt(x^(4) + y^(4) - 2x^(2...

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  15. If 2x^(2) + y^(2) + 6x - 2xy + 9 = 0, then the value of (4x^(3) - y^(3...

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  16. If x + y = 12 and xy = 27, x > y, then the value of (x^3-y^3) is: यद...

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  17. If x^2+y^2+z^2=133,xy +yz + zx = 114 and xyz = 216, then the value of ...

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  18. If 3 sqrt3 x^3-2sqrt2 y^3=(sqrt3x- sqrt2y) (Ax^2+Cxy+By^2), then the v...

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  19. If a + (1)/(a) = 3, then (a^(4) + (1)/(a^(4))) is equal to :

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  20. If a + b + c = 2, a^(2) + b^(2) + c^(2) = 26, then the value of a^(3) ...

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  21. If (x^3-2 sqrt2 y^3) div (x-sqrt2 y)= (Ax^2+Bxy+Cy^2), then, (2A+4 sqr...

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