1 WAEC Mathematics 2021 questions with verified answers and worked explanations. Here are the first 1 — sign up free to practise the full paper.
If (x + 2) and (x - 1) are factors of the expression , find the values of L and k.
According to the factor theorem, if (x + 2) is a factor of the polynomial, then substituting x = -2 into the expression will give zero, which gives the equation 8k - 2L + 24 = 0. Similarly, since (x - 1) is a factor, substituting x = 1 will also give zero, leading to the equation 2k + L + 24 = 0. Solving these two linear equations simultaneously gives the values k = -6 and L = -12.
Common mistake: Students often make a sign error by substituting x = 2 instead of x = -2 for the factor (x + 2), which leads to an incorrect set of simultaneous equations.