Equasion 1 ax+by=c equasion 2 dx+ey=f
a, b,c, d,e and f are non zero real numbers which of the following could replace equasion 1 and still have the same solution

The multiplication property of zero states that the product of any number and 0 is 0. what must be true about either a or b to make ab=0

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?

Which of these sequences is a geometric sequence a 1,2,4, 7, 11, 16, 22. b. 2.4.8.14.22.38 c.3.6.9. 15.18,21 d. 3,9,27,81,243,729,