The expression x squared minus 3x minus 10 factors as (x + a)(x + b). What is the smaller of a and b?

Correct answer to question 66 (Mathematics Knowledge): -5

Method

Look for two numbers multiplying to -10 and adding to -3. They are 2 and -5, so the factorisation is (x + 2)(x - 5) and the smaller value is -5. One number must be negative because the product is negative.