Basic exponential function
f(x)=ax,a>0, a=1 Scaled exponential function
f(x)=Aax Natural exponential function
f(x)=ex,e≈2.71828 Basic exponential domain and range
D=R,R=(0,∞) Basic exponential intercept
a0=1⟹(0,1) Basic exponential asymptote
Discrete exponential model
Percentage growth
A=A0(1+r)n Percentage decay
A=A0(1−r)n Compound interest
A=P(1+mr)mt Continuous model
A=A0ekt Discrete-continuous connection
b=ek,k=lnb Doubling time
T2=kln2,k>0 Half-life
T21=∣k∣ln2,k<0 Exponential-logarithmic equivalence
logax=y⟺ay=x Logarithm restrictions
a>0,a=1,x>0 Fundamental values
loga1=0,logaa=1 Natural inverse identities
ln(ex)=x,elnx=x (x>0) Basic logarithmic domain and range
D=(0,∞),R=R Basic logarithmic intercept
loga1=0⟹(1,0) Basic logarithmic asymptote
Inverse pair
f(x)=ax,f−1(x)=logax Inverse compositions
loga(ax)=x,alogax=x (x>0) Reflected points
(p,q)⟷(q,p) Product law
loga(MN)=logaM+logaN Quotient law
loga(NM)=logaM−logaN Power law
loga(Mp)=plogaM Argument conditions
M>0,N>0 Change of base
logax=logbalogbx=lnalnx Common calculator form
logax=logalogx Equal-base principle
au=av⟹u=v General exponential solution
ax=b⟹x=lnalnb Natural exponential solution
ekx=c⟹x=klnc Single-log equation
logaF(x)=c⟺F(x)=ac Equal-log principle
logaM=logaN⟹M=N Logarithmic domain
M>0,N>0 Transformed exponential
y=AaB(x−h)+k Transformed logarithm
y=Aloga(B(x−h))+k Logarithmic domain condition
Time to a target
A0bt=T⟹t=lnbln(A0T) Continuous time to a target
A0ekt=T⟹t=kln(A0T) Half-life model
A=A0(21)ht Intersection method
Y1=F(x),Y2=G(x) Root method
Y1=F(x)−G(x) Approximation notation
x=ln3ln7−1≈0.771 Logarithmic validity check
every original argument>0