Question 947532
(x-3y+z)(5x+5y+z)
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= x*(5x+5y+z) - 3y*(5x+5y+z) + z*(5x+5y+z)
= {{{5x^2+5xy+xz - 15xy-15y^2-3yz + 5xz+5yz+z^2}}}
= {{{5x^2 - 15y^2 + z^2 - 10xy + 6xz + 2yz}}}