Question 47 of 49advanced🔍 AnalyzeLong Answer5 marks

Let p(x)=ax+bp(x) = ax + b and q(x)=cx+dq(x) = cx + d be two linear polynomials such that: (i) p(0)=5p(0) = 5. (ii) The polynomial p(x)−q(x)p(x) - q(x) cuts the x-axis at (3,0)(3, 0). (iii) The sum p(x)+q(x)p(x) + q(x) is equal to 6x+46x + 4 for all real xx. Find the polynomials p(x)p(x) and q(x)q(x).

(i)

p(0) = 5.

Answer

b = 5

(ii)
Answer

d = -1, a - c = -2

(iii)
Answer

a = 2, c = 4

Explanation

The question requires finding two linear polynomials p(x)=ax+bp(x) = ax + b and q(x)=cx+dq(x) = cx + d using three given conditions.

From condition (i), we find b=5b = 5 since p(0)=a(0)+b=5p(0) = a(0) + b = 5.

From condition (iii), equating coefficients of p(x)+q(x)=6x+4p(x) + q(x) = 6x + 4 gives a+c=6a + c = 6 and b+d=4b + d = 4, allowing us to find d=−1d = -1.

From condition (ii), since p(x)−q(x)p(x) - q(x) cuts the x-axis at (3,0)(3,0), substituting x=3x = 3 gives 3(a−c)+(b−d)=03(a - c) + (b - d) = 0, yielding a−c=−2a - c = -2.

Solving the system of equations a+c=6a + c = 6 and a−c=−2a - c = -2 gives a=2a = 2 and c=4c = 4.