Step-by-step explanation:
8x² + 7y² - z² + 2yz + 3xz - 5xy
x 2x - 3y
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-24x²y - 21y³ + 3yz² - 6y²z - 9xyz + 15xy²
+ 16x³ + 14xy² - 2xz² + 4xyz + 6x²z - 10x²y
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16x³-21y³-34x²y+6x²z+29y²x-6y²z-2xz²+3yz²-5xyz
