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Review of Exponential Functions y = bx

An exponential function has the form f(x)=bxf\left(x\right)=b^x for any positive real number bb, b1b\ne1.

Properties
  • f(x)f\left(x\right) has a horizontal asymptote at y=0y=0
  • The y-intercept is (0, 1)\left(0,\ 1\right)
  • Domain: xRx\in R; Ranage y>0y>0

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Inverse Function -- f(x)=logbxf\left(x\right)=\log_bx
  • y=logbx      x=by\boxed{y=\log_bx\ \ \ \leftrightarrow\ \ \ x=b^y}
  • blogbx=x\boxed{b^{\log_bx}=x} and logb(bx)=x\boxed{\log_b\left(b^x\right)=x}
  • The x-intercept is (1, 0)\left(1,\ 0\right)
  • Domain: x>0x>0; Range: yRy\in R
  • It has a vertical asymptote at x=0x=0

Practice: Limits Exponential Functions

Use the graph of the exponential function to evaluate the following limits
If the limit approaches \infty or -\infty, enter \infty or -\infty instead of DNE.

Review of Exponential Rules

  • axay=ax+y\displaystyle a^{\orange{x}}\cdot a^{\green{y}}=a^{\orange{x}+\green{y}}
  • axay=axy\displaystyle \frac{a^{\orange{x}}}{a^{\green{y}}}=a^{\orange{x}-\green{y}}
  • (ax)y=axy\displaystyle \left(a^{\orange{x}}\right)^{\green{y}}=a^{\orange{x}\green{y}}
  • (ab)x=axbx\displaystyle \left(a\cdot b\right)^{\orange{x}}=a^{\orange{x}}\cdot b^{\orange{x}}
  • (ab)x=axbx\displaystyle \left(\frac{a}{b}\right)^{\orange{x}}=\frac{a^{\orange{x}}}{b^{\orange{x}}}