2014 · Q47
If (x + k) is the common factor of x² + ax + b and x² + cx + d, then what is k equal to?
Elementary MathematicsAlgebra
- A(d − b)/(c − a)
- B(d − b)/(a − c)
- C(d + b)/(c + a)
- D(d − b)/(c + a)
Explanation
x = −k satisfies both: k² − ak + b = 0 and k² − ck + d = 0; subtracting gives k(c − a) = d − b.