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Math Challenge II-A Wk1 HW 1.22

 
 
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Math Challenge II-A Wk1 HW 1.22
by Zhi Feng Etan Kiang - Thursday, June 4, 2020, 12:01 PM
 
I'm stuck on this problem, and I tried rearranging the problem to be x3-z3-(8y3+6xyz) and then (x-z)(x2+xz+z2)-(2y(4y2+3xz)), but i can't continue after that. Please help me, and thank you!
 
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Re: Math Challenge II-A Wk1 HW 1.22
by Areteem Professor - Thursday, June 4, 2020, 1:12 PM
 

Note that the first three terms are all cubes: $x^3$, $(-z)^3$, and $(-2y)^3$. Take a look at the commonly used formulas listed at the beginning of the chapter in your book. Which of those involve the sum of  three cubes?

 
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