Use complete sentences to describe why √-1 ≠ -√1

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

which of the following sets of data would produce the largest value for an independent-measures t statistic? the two sample means are 10 and 20 with variances of 20 and 25 the two sample means are 10 and 20 with variances of 120 and 125 the two sample means are 10 and 12 with sample variances of 20 and 25 the two sample means are 10 and 12 with variances of 120 and 125

Can anyone explain to me how to do this? anything will .