∑ DANEMATHICS
FREE CAPS MATHS RESOURCES
Grade 11 · Equations
Solving Quadratic Equations: Every Method & Type
MEMORANDUM
Name:
Class:
Date:
Mark
/ 20
Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.
- 1Solve x2 − 7x + 12 = 0. (factorise)(2)(x−3)(x−4)=0 → x = 3 or 4✓✓ (2)
- 2Solve x2 + 2x − 8 = 0. (factorise)(2)(x+4)(x−2)=0 → x = −4 or 2✓✓ (2)
- 3Solve x2 − 9x = 0. (common factor)(2)x(x−9)=0 → x = 0 or 9✓✓ (2)
- 4Solve x2 − 16 = 0. (difference of squares)(2)(x−4)(x+4)=0 → x = ±4✓✓ (2)
- 5Solve x2 + 4x + 1 = 0 (formula, 2 dp). (formula)(2)x = (−4±12)/2 ≈ −0,27 or −3,73✓✓ (2)
- 6Solve 2x2 − 5x + 1 = 0 (formula, 2 dp). (formula)(2)x = (5±17)/4 ≈ 2,28 or 0,22✓✓ (2)
- 7Solve x2 = 2x + 15. (rearrange)(2)x2−2x−15=0 → (x−5)(x+3)=0 → x = 5 or −3✓✓ (2)
- 8Solve 2x2 + 7x + 3 = 0. (leading coeff)(2)(2x+1)(x+3)=0 → x = −12 or −3✓✓ (2)
- 9Solve x + 5x = 6. (fraction)(2)x2−6x+5=0 → (x−1)(x−5)=0 → x = 1 or 5✓✓ (2)
- 10Solve (x − 2)(x + 1) = 4. (expand first)(2)x2−x−2=4 → x2−x−6=0 → (x−3)(x+2)=0 → x = 3 or −2✓✓ (2)
TOTAL: 20 marks