Algebra 2 Intermediate

Exponential Equations

Solve equations of the form aˣ = b using logarithms — same base method and the general log/ln method — with step-by-step work showing every arithmetic detail.

Live Calculator · Step-by-Step · Algebra 2
Equation Setup
3ˣ = 81
Solve aˣ = b for x. Base must be positive and not equal to 1.
Examples
2^(3x − 1) = 32
Solves acx+d = b. Equation form: cx + d = loga(b), then solve for x.
Examples
5ˣ = 2 · 3ˣ
Solves aˣ = b·cˣ. Rearranges to (a/c)ˣ = b → x = log(b)/log(a/c).
Examples
Solution
Enter values above and press Solve to see the solution, exact log form, and a verification check.
Solution
Exact Form (Log)
Verification Check
Step-by-Step Solution
Two Methods for Exponential Equations
Method 1 — Same Base: aˣ = aⁿ → x = n

Same Base Method: If you can rewrite both sides using the same base — for example, 8 = 2³ — then set the exponents equal and solve. This gives an exact integer answer with no calculator needed.

Log Method: When the same base trick isn't obvious, take log (or ln) of both sides. The Power Rule lets you bring the exponent down as a multiplier:

aˣ = b  →  log(aˣ) = log(b)  →  x · log(a) = log(b)  →  x = log(b) / log(a)

Both log base 10 and natural log (ln) give the same answer because the log base cancels in the ratio.

When solving a^(cx+d) = b: first find the exponent value using logs, then solve the resulting linear equation cx + d = log_a(b) for x.
Change of Base Formula
x = log_a(b) = log(b)/log(a) = ln(b)/ln(a)

Logarithms of the same base or natural log both work — choose whichever is cleaner. The ratio is what matters, not the base you pick.

For aˣ = b·cˣ: Divide both sides by cˣ first:

(a/c)ˣ = b  →  x = log(b) / log(a/c)

This works as long as a ≠ c (otherwise the bases cancel and there is no exponential to solve).

  • Always check: is b a perfect power of a? Try same-base first.
  • Base a must be positive and not equal to 1.
  • b must be positive for real solutions (log of negative is undefined).
  • Negative x values are completely valid — they just mean a fractional result.

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