什么是(sqrt(5+)sqrt(3))/(sqrt(3+)sqrt(3+)sqrt(5)) - (sqrt(5-)sqrt(3))/(sqrt(3+)sqrt (3-)SQRT(5))?
2/7我们采取,A =(sqrt5 + sqrt3)/(sqrt3 + sqrt3 + sqrt5) - (sqrt5-sqrt3)/(sqrt3 + sqrt3-sqrt5)=(sqrt5 + sqrt3)/(2sqrt3 + sqrt5) - (sqrt5 -sqrt3)/(2sqrt3-sqrt5)=(sqrt5 + sqrt3)/(2sqrt3 + sqrt5) - (sqrt5-sqrt3)/(2sqrt3-sqrt5)=((sqrt5 + sqrt3)(2sqrt3-sqrt5) - (sqrt5-sqrt3) )(2sqrt3 + sqrt5))/((2sqrt3 + sqrt5)(2sqrt3-sqrt5)=((2sqrt15-5 + 2 * 3-sqrt15) - (2sqrt15 + 5-2 * 3-sqrt15))/((2sqrt3) ^ 2-(sqrt5)^ 2)=(取消(2sqrt15)-5 + 2 * 3cancel(-sqrt15) - 取消(2sqrt15)-5 + 2 * 3 +取消(sqrt15))/(12-5)=( -10 + 12)/ 7 = 2/7请注意,如果在分母中(sqrt3 + sqrt(3 + sqrt5))和(sqrt3 + sqrt(3-sqrt5))那么答案将会改变。
你如何简化(1 / sqrt(a-1)+ sqrt(a + 1))/(1 / sqrt(a + 1)-1 / sqrt(a-1))div sqrt(a + 1)/( (a-1)sqrt(a + 1) - (a + 1)sqrt(a-1)),a> 1?
巨大的数学格式......>颜色(蓝色)(((1 / sqrt(a-1)+ sqrt(a + 1))/(1 / sqrt(a + 1)-1 / sqrt(a-1)) )/(sqrt(a + 1)/((a-1)sqrt(a + 1) - (a + 1)sqrt(a-1)))=颜色(红色)(((1 / sqrt(a-) 1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a-1))))/(sqrt(a) +1)/(sqrt(a-1)cdot sqrt(a-1)cdot sqrt(a + 1)-sqrt(a + 1)cdot sqrt(a + 1)sqrt(a-1)))= color(蓝色)(((1 / sqrt(a-1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a -1))))/(sqrt(a + 1)/(sqrt(a + 1)cdot sqrt(a-1)(sqrt(a-1)-sqrt(a + 1)))=颜色(红色) ((1 / sqrt(a-1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a-1) ))xx(sqrt(a + 1)cdot sqrt(a-1)(sqrt(a-1)-sqrt(a + 1))
简化表达式?:1 /(sqrt(144)+ sqrt(145))+ 1 /(sqrt(145)+ sqrt(146))+ ... + 1 /(sqrt(168)+ sqrt(169))
1首先注意:1 /(sqrt(n + 1)+ sqrt(n))=(sqrt(n + 1)-sqrt(n))/((sqrt(n + 1)+ sqrt(n))( sqrt(n + 1)-sqrt(n))颜色(白色)(1 /(sqrt(n + 1)+ sqrt(n)))=(sqrt(n + 1)-sqrt(n))/(( n + 1)-n)颜色(白色)(1 /(sqrt(n + 1)+ sqrt(n)))= sqrt(n + 1)-sqrt(n)所以:1 /(sqrt(144)+ sqrt(145))+ 1 /(sqrt(145)+ sqrt(146))+ ... + 1 /(sqrt(168)+ sqrt(169))=(sqrt(145)-sqrt(144))+ (sqrt(146)-sqrt(145))+ ... +(sqrt(169)-sqrt(168))= sqrt(169)-sqrt(144)= 13-12 = 1