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  1. AP Pre Calculus
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How do you solve an exponential equation of the form ax=ba^x = bax=b?

Take the logarithm of both sides with base a: x=log⁡a(b)x = \log_a(b)x=loga​(b). Or, take the natural logarithm: x=ln⁡(b)ln⁡(a)x = \frac{\ln(b)}{\ln(a)}x=ln(a)ln(b)​

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How do you solve an exponential equation of the form ax=ba^x = bax=b?

Take the logarithm of both sides with base a: x=log⁡a(b)x = \log_a(b)x=loga​(b). Or, take the natural logarithm: x=ln⁡(b)ln⁡(a)x = \frac{\ln(b)}{\ln(a)}x=ln(a)ln(b)​

How do you solve a logarithmic equation of the form log⁡b(x)=a\log_b(x) = alogb​(x)=a?

Rewrite the equation in exponential form: x=bax = b^ax=ba.

Steps to solve: log⁡b(x+2)+log⁡b(x)=c\log_b(x+2) + \log_b(x) = clogb​(x+2)+logb​(x)=c?

  1. Use product rule: log⁡b((x+2)x)=c\log_b((x+2)x) = clogb​((x+2)x)=c. 2. Convert to exponential form: (x+2)x=bc(x+2)x = b^c(x+2)x=bc. 3. Solve the quadratic equation. 4. Check for extraneous solutions.

Steps to solve: af(x)=ag(x)a^{f(x)} = a^{g(x)}af(x)=ag(x)

  1. Since the bases are equal, set the exponents equal to each other: f(x)=g(x)f(x) = g(x)f(x)=g(x). 2. Solve for x. 3. Check for extraneous solutions.

Steps to solve: af(x)=ba^{f(x)} = baf(x)=b?

  1. Take the logarithm of both sides (either base a or natural log). 2. Solve for x. 3. Check for extraneous solutions.

Steps to find the inverse of y=2ex+1−3y = 2e^{x+1} - 3y=2ex+1−3?

  1. Swap x and y: x=2ey+1−3x = 2e^{y+1} - 3x=2ey+1−3. 2. Isolate the exponential term: (x+3)/2=ey+1(x+3)/2 = e^{y+1}(x+3)/2=ey+1. 3. Take the natural log: ln⁡((x+3)/2)=y+1\ln((x+3)/2) = y+1ln((x+3)/2)=y+1. 4. Solve for y: y=ln⁡((x+3)/2)−1y = \ln((x+3)/2) - 1y=ln((x+3)/2)−1.

Steps to find the inverse of y=log⁡3(x−2)+1y = \log_3(x-2) + 1y=log3​(x−2)+1?

  1. Swap x and y: x=log⁡3(y−2)+1x = \log_3(y-2) + 1x=log3​(y−2)+1. 2. Isolate the log term: x−1=log⁡3(y−2)x-1 = \log_3(y-2)x−1=log3​(y−2). 3. Convert to exponential form: 3x−1=y−23^{x-1} = y-23x−1=y−2. 4. Solve for y: y=3x−1+2y = 3^{x-1} + 2y=3x−1+2.

What is the product rule for logarithms?

log⁡b(MN)=log⁡b(M)+log⁡b(N)\log_b(MN) = \log_b(M) + \log_b(N)logb​(MN)=logb​(M)+logb​(N)

What is the quotient rule for logarithms?

log⁡b(M/N)=log⁡b(M)−log⁡b(N)\log_b(M/N) = \log_b(M) - \log_b(N)logb​(M/N)=logb​(M)−logb​(N)

What is the power rule for logarithms?

log⁡b(Mp)=p⋅log⁡b(M)\log_b(M^p) = p \cdot \log_b(M)logb​(Mp)=p⋅logb​(M)

What is the change of base formula for logarithms?

log⁡b(M)=log⁡c(M)log⁡c(b)\log_b(M) = \frac{\log_c(M)}{\log_c(b)}logb​(M)=logc​(b)logc​(M)​

General form of exponential function with transformations

f(x)=abx−h+kf(x) = ab^{x-h} + kf(x)=abx−h+k

General form of logarithmic function with transformations

f(x)=alog⁡b(x−h)+kf(x) = a \log_b(x-h) + kf(x)=alogb​(x−h)+k

Inverse of exponential function f(x)=abx−h+kf(x) = ab^{x-h} + kf(x)=abx−h+k

f−1(x)=h+ln⁡((x−k)/a)ln⁡(b)f^{-1}(x) = h + \frac{\ln((x-k)/a)}{\ln(b)}f−1(x)=h+ln(b)ln((x−k)/a)​

Inverse of logarithmic function f(x)=alog⁡b(x−h)+kf(x) = a \log_b(x-h) + kf(x)=alogb​(x−h)+k

f−1(x)=b(x−k)a+hf^{-1}(x) = b^{\frac{(x-k)}{a}} + hf−1(x)=ba(x−k)​+h

What are the key differences between solving exponential equations and logarithmic equations?

Exponential: Isolate exponential term, take logarithm. Logarithmic: Isolate log term, convert to exponential form. Extraneous solutions are more common in logarithmic equations.

Compare the domain restrictions of exponential and logarithmic functions.

Exponential: Domain is all real numbers. Logarithmic: Domain is positive real numbers (argument must be > 0).