This is from OG Review 11th edition p. 290, #142.
If X is an integer, is 9^x + 9^-x = b?
2) x> 0 = b.
The book says that the second condition "x > 0 = b" is not sufficient because it gives no information about the relationship between x and b.
However I see it as this: "9^b + 1/(9^b) = b". This equation can't happen so it does answer the question posed. Thus the second condition is sufficient.
Anyone know what's up? Thanks!
If X is an integer, is 9^x + 9^-x = b?
2) x> 0 = b.
The book says that the second condition "x > 0 = b" is not sufficient because it gives no information about the relationship between x and b.
However I see it as this: "9^b + 1/(9^b) = b". This equation can't happen so it does answer the question posed. Thus the second condition is sufficient.
Anyone know what's up? Thanks!
