函數的複雜困難的題目!?

5.
y = log(a,x) + b
y = (log x)/(log a) + b ...... ①

When x = 1, y = (log 1)/(log a) + b = 0 + b = b
From the graph, the y - intercept of ① > 0
∴ b > 0

When x is increasing, y is increasing
1/(log a) > 0
log a > 0
a > 1

∴ D. a > 1 and b > 0


6.
y = a^x
y is increasing when x is increasing
∴ a > 1

y = b^x
y is decreasing when x is increasing
∴ 0 < b < 1

When x = 0, y = a^0 = b^0 = 1
∴ k = 1

Since y = 1/b^x may not be equal to y = a^x,
ab may not be equal to 1

∴ A