Real numbers a and b satisfy
a + ab = 250
a - ab = -240
Enter all possible values of a, separated by commas.
If you add the two equations together a + ab = 250
a – ab = –240
———————
you get 2a = 10
from which a = 5
The problem doesn't ask for b,
but ... find b by substituting
a back into a + ab = 250 5 + 5b = 250
5b = 245
b = 49
check b by substituting
a back into a – ab = –240 5 – 5b = –240
–5b = –245
b = 49
