问道数学题

longger

(x^2-25)^2=x^2-10x+25的解得集合有几个数？
a)0
b)1
c)2
d)3
e)4

bloomingtrees

C

bloomingtrees

不好意思..說錯了...應該是3個...

(x+5)^2(x-5)^2=(x-5)^2

(x-5)^2  *  <(x+5)^-1> =0

(x-5)^2 (x^2+10x+26)(x^2+10x+24)=0

b^2 - 4ac>=0才有解...故x^2+10x+26<0無解...x^2+10x+24有兩解...(x-5)^2 有一解...共三解

longger

3x so much ! i've got it!