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HowToSolveIt:x·√(15^2-x^2)20ptsHowToSolveIt:x·√(15^2-x^2)x·√(15^2-x^2)=108

题目详情
How To Solve It:x·√(15^2-x^2) 20pts
How To Solve It:
x·√(15^2-x^2)
x·√(15^2-x^2)=108
▼优质解答
答案和解析
x·√(15^2-x^2)=108
x^2(15^2-x^2)=108^2
x^4-225x^2+108^2=0
(x^2-81)(x^2-144)=0
x^2=81or x^2=144
so x=9or x=-9or x=12or x=-12