Home›Calculus 1›Exponential and logarithmic equations›Problem 13.381

Exponential and logarithmic equations

Problem 13.381 · easy

Solve \( \displaystyle 2 e^{3 x} = 20 \) exactly.

Divide out the coefficient, then take ln of both sides.
Reviewed
\[ \left. 2 e^{3 x} - 20 \right|_{\substack{ x=\frac{\ln{\left(10 \right)}}{3} }} = 0 \]
x = log(10)/3 satisfies the equation.✓ Proved

Answer \( x = \frac{\ln{\left(10 \right)}}{3} \)

✓ Nihil obstat Lines: 1 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. How we verify

The full receipt

Line	Status	Checked by	Detail
1	Reviewed	reviewers: gpt-oss:20b, qwen3.6:27b-mlx	a sentence; read, not computed
2	✓ Proved	sympy 1.14.0	simplify(lhs - rhs) reduced to 0
answer, a second way	✓ Checked independently	sympy 1.14.0 + mpmath 1.3.0	Newton's method over [−20, 20] finds exactly the claimed real roots

Reviewers

gpt-oss:20b: pass
qwen3.6:27b-mlx: pass — The solution correctly identifies the algebraic steps required to isolate x and provides the exact solution. The verification step confirms the result.

Every verdict on record (6)

qwen3.6:27b-mlx: pass 2026-10-19 — The solution correctly identifies the algebraic steps required to isolate x and provides the exact solution. The verification step confirms the result.
gpt-oss:20b: pass 2026-10-19
qwen3.6:27b-mlx: pass 2026-10-18 — The solution correctly identifies the algebraic steps (dividing by 2 and taking the natural logarithm) and verifies the result. The logic is sound and complete for an exact solution.
gpt-oss:20b: pass 2026-10-18
qwen3.6:27b-mlx: pass 2026-10-18 — The solution correctly identifies the algebraic steps (dividing by 2, then taking the natural logarithm) and provides the correct exact solution. The verification step confirms the result.
gpt-oss:20b: pass 2026-10-18

Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence, not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by generator:structured/log_exp_equations, checked 2026-10-19 with SymPy 1.14.0.