Mathematics for IGCSE & O level - Algebraic Manipulation (Section 6 - No. 44)
When factorizing x² + bx + c and 'c' is negative, what is the rule for the signs of the factors?
Both factors are positive.
Both factors are negative.
The factors must have different signs.
Both factors have the same sign as the coefficient of 'b'.
Giải thích
If 'c' is negative, the factors must have opposite signs.