Question

二次根式求解

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Answer 1

(4) (√5+6)/(√5-6)+(√7+2)/(√7-2)
=(√5+6)^2/(5-36)+(√7+2)^2/(7-4)
=(41+12√5)/(-31)+(11+4√7)/3
=-(123+36√5)/93+(341+124√7)/93
=(218-36√5+124√7)/93。
(8) √15÷(1/√3+1/√2)
=√15÷(√3/3+√2/2)
=√15÷[(2√3+3√2)/6]
=√15x6/(2√3+3√2)
=√15x6(2√3-3√2)/[(2√3+3√2)(2√3-3√2)]
=(12√45-18√30)/(-6)。
(3) 原式=√(x-y)/y+x√(x-y)/(x-y)-√(x-y)
=√(x-y)[1/y+x/(x-y)-1]
=√(x-y)[(x-y+xy-xy+y)/y(x-y0]
=x√(x-y)/y(x-y)。
=-6√5+3√30。