u,v,w,x,y和z的音标分别是什么?答:u,v,w,x,y和z的读音:英式音标:[juː] , [viː], [ˈdʌbljuː] , [eks] , [waɪ],[zed]美式音标:[juː] , [viː] , [ˈdʌbljuː] , [eks] , [waɪ],[zi]英文字母,即现在英文(English)所基于的...
已知x,y,z,w为正整数,且x<y<z<w,求使1/x+1/y+1/z+1/w是正数的所有有序...答:得到一组满足条件的解(1, 2, 3, 6).1/x+1/y+1/z+1/w = 1.首先有x > 1, 即x ≥ 2.若x ≥ 3, 则y ≥ 4, z ≥ 5, w ≥ 6, 1/x+1/y+1/z+1/w ≤ 1/3+1/4+1/5+1/6 = 19/20 < 1.∴ x = 2, y ≥ 3.∵1 = 1/x+1/y+1/z+1/w < 1/x+1/y...