Fall 2026 errata

The following errors have been reported:

• 1.1 Trigonometric identities: x should be y on the vertical leg of the triangle (Katie Anderson).
• 1.2 Eq. (1): \cos -> \sin in \csc (Zoe Parten).
• 1.2 Eq. (3): should be \sin(A+B) = \cos A \sin B + \sin A \cos B (Zoe Parten).
• 1.3 after Eq. (8): \epsilon needs $$, exsit -> exist (Katie Anderson).
• 1.5 Eq. (14): 2x^2 + 3 -> 2x^2 + 5 (Zoe Parten).
• 1.5 Eq. (24): answer should be (-2x^5 +4x^3 + 4x)/ (x^8 + 4x^4 +4) (Zoe Parten).
• 1.5 Eq. (27): definition of u is missing, should be (x-1)(x^2 - 2x) (Zoe Parten).
• 1.5 before Eq. (41): problem statement \sin x -> 4 \sin x (Zoe Parten).
• 1.3 Eq. (19): x+1 -> x-1 in numerator and denominator (Katie Anderson).
• 3.1 Eq. (13): this example was supposed to be for subtraction, and the matrices on the left are in the wrong order. They should be swapped here, then the result should be [6 4 3; 6 3 2]. The example should be copied to subtraction with the order swapped. (Zoe Parten)
• 3.1 Eq. (15): -2 x 4 -> -2 x -2 (Zoe Parten).
• 3.3 Eq. (23): the first equation should be x_2 + x_3 = -2 (Jackson Brickey).
• 3.3 Eq. (25): the coefficient of x_3 in the first equation should be 4 (Andrew Turkiewicz).
• 3.3 Eq. (29): the last element of the initial augmented matrix should be 2 not -2 (Andrew Turkiewicz).
• 4.2 Eq. (8): missing comma between roots.
• 5.5 Eq. (4): ^2 is in the wrong spot, should go in denominator.
• 7.2 Eq. (3): y' should be y''.
• 7.4 Eq. (9): \lambda+1 should be \lambda-1.
• 7.4 Eq. (30): equation needs line break
• 7.5 Eq. (11): -1.5x should be in the exponent.
• 7.5 Eq. (34): equation needs line break

Start from the linked Trigonometric identities page and locate the listed sections and equation numbers throughout the textbook. Work through the checklist, correcting the reported text, equations, matrices, and formatting, then verify the rendered pages show each correction.