SOLUTION: **these problems has to be factored.... please help... i have been doing these problems for homework and these are my last four.*****they are due tomorrow. we had a week to do...61

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: **these problems has to be factored.... please help... i have been doing these problems for homework and these are my last four.*****they are due tomorrow. we had a week to do...61      Log On


   

Question 177417: **these problems has to be factored.... please help... i have been doing these problems for homework and these are my last four.*****they are due tomorrow. we had a week to do...614 problems....please help
612) 9x5 – 18x4 = 9x^4(x-2)

613) z4 – 16=(z^2+4)*(z^2+4)*(z-2)*(z+2)

614) x3 – 27=(x-3)*(x^2+3x+9)

615) Solve: 25x2 – 64 = 0

Found 2 solutions by stanbon, jim_thompson5910:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
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.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
612) Correct


613) Close, but z%5E4-16=%28z%5E2%2B4%29%28z-2%29%28z%2B2%29


614) Correct


615)




25x%5E2-64=0 Start with the given equation


%285x%2B8%29%285x-8%29=0 Factor the left side (use the difference of squares)



Now set each factor equal to zero:

5x%2B8=0 or 5x-8=0


x=-8%2F5 or x=8%2F5 Now solve for x in each case


So the answers are

x=-8%2F5 or x=8%2F5