问题
填空题
设x=y+z=2,则x3+2y3+2z3+6xyz=______.
答案
∵x=y+z=2,
∴x3+2y3+2z3+6xyz
=x3+2y3+2z3+6(y+z)yz
=x3+2(y3+z3+3y2z+3yz2)
=x3+2(y+z)3
=23+2×23
=8+16
=24.
故答案为:24.
设x=y+z=2,则x3+2y3+2z3+6xyz=______.
∵x=y+z=2,
∴x3+2y3+2z3+6xyz
=x3+2y3+2z3+6(y+z)yz
=x3+2(y3+z3+3y2z+3yz2)
=x3+2(y+z)3
=23+2×23
=8+16
=24.
故答案为:24.