Mathematics
The four strands
Grade 9 mathematics tests number (powers, square roots, rational numbers), patterns and relations (polynomials, linear relations, equations, inequalities), shape and space (circle geometry, surface area, volume, similarity), and statistics and probability.
Traps
Negative bases and exponents: −3² = −9, but (−3)² = +9. When you subtract a polynomial, distribute the negative to every term. When you multiply or divide an inequality by a negative, reverse the sign. Slope is rise over run with signs carried along - a line falling from left to right has negative slope. In circle geometry, an inscribed angle is half the central angle standing on the same arc, and a tangent meets the radius at 90°. For composite objects, add or subtract only the faces actually exposed; a floor or a wall is not painted. Volume carries cubic units, area square units. In a data set skewed by one large value, the median describes the typical value better than the mean.
Worked example
Solve −2x + 5 > 11. Subtract 5: −2x > 6. Divide by −2 and flip: x < −3. Check x = −4: −2(−4) + 5 = 13 > 11 ✓. Check x = 0: 5 > 11 ✗, so the direction is correct.
Rule of thumb
Solve, then substitute your answer back into the original equation or inequality. Substitution catches sign and distribution errors faster than re-reading your work.