Question

a^3+b^3+c^3+(1/a+1/b+1/c)^3大于等于18

速度我着急

Answer 1

a^3+b^3+c^3+(1/a+1/b+1/c)^3
≥枝败3(a^3.b^3.c^3)^(1/3)+[3(1/a.1/b.1/c)^(1/3)]^3
=3abc+(27/abc)
≥猛咐颤2√简枣(3abc*27/abc)
=2√81
=18

Answer 2

a^3+b^3+c^3大于等于3abc，（1/a+1/b+1/c)^3大于等于27/abc，原式橡兄大于等于3（abc+9/abc）大于等于梁局袭3*2*根号腊举9=18

追问

写全点 可以不

追答

用的全是算术—几何均值不等式。