which three statements are true?

a) if x= -10^4 then log 10 = -4
b)if x= 2^8 then log 2x = 8
c) log2 2= 4
d) if x= 3 then log10 3=x
e) log 10 256-2log 10 a/log 10 b
f)log 10 (a-b)= log 10 a/log 10 b
g) the gradient of the graph of y= 2x^x at x= 2 is 2e^e
h) the gradient of the graph of y= e^x at x= 2is 2e

can you explain why? I don't get this

which three statements are true?

a) if x= -10^4 then log 10 = -4
b)if x= 2^8 then log 2x = 8
c) log2 2= 4
d) if x= 3 then log10 3=x
e) log 10 256-2log 10 a/log 10 b
f)log 10 (a-b)= log 10 a/log 10 b
g) the gradient of the graph of y= 2x^x at x= 2 is 2e^e
h) the gradient of the graph of y= e^x at x= 2is 2e

a, b