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OpenStudy (anonymous):
x^3+512=0 please i need to see steps
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OpenStudy (mathstudent55):
Is 512 a perfect cube?
OpenStudy (mathstudent55):
\(a^3 - b^3 = (a - b)(b^2 + ab + b^2) \)
OpenStudy (anonymous):
okay
OpenStudy (mathstudent55):
512 = 8^3
OpenStudy (mathstudent55):
Sorry, you need the sum of two cubes, not the difference.
\(\large a^3 + b^3 = (a + b)(a^2 - ab + b^2)\)
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OpenStudy (mathstudent55):
You have
\(\large x^3 + 8^3 = 0\)
Now just factor following the sum of two cubes pattern just above.
OpenStudy (mathstudent55):
\(\large (x + 8)(x^2 - 8x + 64) = 0 \)
\(\large x + 8 = 0\) or \(\large x^2 - 8x + 64 = 0 \)
OpenStudy (mathstudent55):
The left equation is simple.
Use the quadratic formula on the right equation.
OpenStudy (anonymous):
looking for how to breakdown -192
OpenStudy (anonymous):
on the root
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OpenStudy (mathstudent55):
\(x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)
\(x = \dfrac{-(-8) \pm \sqrt{(-8)^2 - 4(1)(64)}}{2(1)} \)
OpenStudy (mathstudent55):
\(x = \dfrac{8 \pm \sqrt{64 - 256}}{2} \)
\(x = \dfrac{8 \pm \sqrt{-192}}{2} \)
OpenStudy (mathstudent55):
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