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- List the given numbers and units.
- Choose the formula that matches the asked value.
- Simplify carefully and compare with options.
Correct Answer: C
Correct Answer: C
Method / Topic: Quadratic Equations
The answer follows from the arithmetic relation between the given values.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Quadratic Equations
Use factorisation, the quadratic
, the discriminant, or the relations between roots and coefficients as appropriate.
(x - 3)(x - 7) = 0, so the roots are 3 and 7. Their difference is 4.
CHECK:
Substitute the obtained root or derived value back into the original equation or coefficient relation to confirm it.
EXAM TIP:
Before expanding calculations, check whether the quadratic can be factorised quickly or solved directly using sum and product of roots.
Do not forget that for ax² + bx + c = 0, sum of roots is -b/a and product of roots is c/a.
PRACTICAL EXAMPLE:
Quadratic equations are used whenever an unknown quantity appears squared, including geometric dimensions and algebraic optimisation problems.
Therefore, the correct
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Learn + Solve: Shortcut, Trap & Fast Route Click to view shortcut, steps, and common mistake
Shortcut used, common trap, and the fastest solving route
- List the given numbers and units.
- Choose the formula that matches the asked value.
- Simplify carefully and compare with options.
Find the difference between the roots of x² - 10x + 21 = 0.
Explanation
Correct Answer: C
Method / Topic: Quadratic Equations
The answer follows from the arithmetic relation between the given values.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Quadratic Equations
Use factorisation, the quadratic
, the discriminant, or the relations between roots and coefficients as appropriate.
(x - 3)(x - 7) = 0, so the roots are 3 and 7. Their difference is 4.
CHECK:
Substitute the obtained root or derived value back into the original equation or coefficient relation to confirm it.
EXAM TIP:
Before expanding calculations, check whether the quadratic can be factorised quickly or solved directly using sum and product of roots.
Do not forget that for ax² + bx + c = 0, sum of roots is -b/a and product of roots is c/a.
PRACTICAL EXAMPLE:
Quadratic equations are used whenever an unknown quantity appears squared, including geometric dimensions and algebraic optimisation problems.
Therefore, the correct
See full explanation + shortcut trick
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