翻译一道数学题目英译中the difference between a number and its squares is 42_数学解答

翻译一道数学题目英译中
the difference between a number and its squares is 420. find the number
如果能解出来,就更好了,解出来+ 分.谢谢

人气：179 ℃　时间：2020-05-13 09:16:12

解答

一个数与它的平方的差是420,求这个数
xx-x = 420
(x-21)(x+20)=0
x = 21
or
x = -20
x-xx = 420
(x+21)(x-20) = 0
x = -21
x = 20
两种情况,分别有两种答案.加分吗?