2017 · Q15
If (x + 2) is a common factor of x²+ax+b and x²+bx+a, then the ratio a : b is equal to
Elementary MathematicsAlgebra
- A1
- B2
- C3
- D4
Explanation
Since (x+2) is a common factor, x = −2 zeroes both quadratics: 4−2a+b = 0 and 4−2b+a = 0. Subtracting the two equations gives −3a+3b = 0, i.e. a = b. Hence the ratio a:b = 1. Option (A) 1.