<PRE><B>Question 177417</B>
612) 9x^5 – 18x^4 = 9x^4(x-2)
9x^4(x -1) = 9x^4(x-2)
x-1 = x-2
-1 = -2
That is a contradiction.
The problem has no solution
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613) z^4 – 16=(z^2+4)*(z^2+4)*(z-2)*(z+2)
(z^2-4)(z^2+4) = (z^2+4)^2 * (z^2-4)
1 = (z^2+4)
z^2 = -3
z = sqrt(3)i or z = -sqrt(3)i
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614) x^3 – 27=(x-3)*(x^2+3x+9)
That is an identity and is true for all values of x
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615) Solve: 25x2 – 64 = 0 
(5x-8)(5x+8) = 0
x = 8/5 or x = -8/5
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Cheers,
Stan H.
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