1. To prove 1 + 3 + 5 + ... + (2n - 1) = n² by induction, which line correctly uses the k-case to prove the (k + 1)-case?
Assume the sum of the first k odd numbers is k^2. The next odd number is 2k + 1, so the next sum is k² + 2k + 1 = (k + 1)^2.
Use Skill Align for HSC Year 12 Mathematics Extension 1 practice questions and exercise questions after the relevant topic has been taught. Students can start with the pathway demo, then practise by topic and mode.
HSC Year 12 Mathematics Extension 1 includes 30 practice skills across Advanced functions and proof, Calculus and applications, Vectors and complex numbers, and Extension problem solving.
A practice skill is a focused topic or question type designed to help students practise one curriculum-aligned concept with instant feedback and explanations. Skill Align uses practice skills to organise questions by year level, subject, strand, and curriculum focus.
These sample questions are visible on the page before login. They show HSC Year 12 Mathematics Extension 1 induction, vectors, binomial, trigonometry, calculus, and probability explanations before opening the demo.
Assume the sum of the first k odd numbers is k^2. The next odd number is 2k + 1, so the next sum is k² + 2k + 1 = (k + 1)^2.
Since b . a = 11 and a . a = 10, proj_a b = (11 / 10)a. Hence p = b - proj_a b = (-13 / 10, 39 / 10), with magnitude √1690 / 10 = 13sqrt(10) / 10.
The x⁴ term is C(7, 4)(-2x)⁴ = 35 x 16x⁴ = 560x⁴, so the coefficient is 560.
Factor the equation as (2cos x - 1)(cos x + 1) = 0. Thus cos x = 1 / 2 or cos x = -1. On 0 <= x < 2π, these occur at π / 3, 5π / 3 and π, giving three solutions.
On 0 <= x <= 1, x is above x^2. The area is the integral from 0 to 1 of x - x², which is 1 / 2 - 1 / 3 = 1 / 6.
For a binomial random variable, E(X) = np. Here E(X) = 8 x 0.35 = 2.8, meaning the long-run average number of successes is 2.8 per eight trials.
HSC Year 12 Mathematics Extension 1 practice should give strong students enough structure to revise induction, vectors, binomial theorem, trigonometry, calculus, and probability. These examples preview that style before the no-login Extension 1 demo.
Mathematics Extension 1 practice sits inside NSW Year 12 HSC Mathematics course structures, with Year 11 Preliminary context available through the full curriculum coverage, with Skill Align keeping the route focused on the selected maths pathway.
Senior practice is organised by pathway, unit, topic, and mode so students can revise targeted areas rather than sitting a full-paper workflow every time. Skill Align treats practice questions and exercise questions as the same learning workflow: students answer curriculum-aligned questions, review explanations, and move between exercise mode and test mode.
Start with the public sample questions to check the question style, then use the curriculum coverage page to choose a topic that matches the student's current classwork.
These examples are not the full topic list. Use the curriculum coverage page for the complete mapped pathway.
NSW students studying Mathematics Extension 1.
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Public samples are free before sign-in. Regular full subject access uses a parent-managed account with included access to start and an optional monthly subject subscription when more practice is needed. Exam packs are separate one-off PDF purchases.