If the polynomials ax3+4x2+3x−4 and x3−4x+a leave the same remainder when divided by (x - 3), find the value of a.
Let p(x)=ax3+4x2+3x−4 and q(x)=x3−4x+a be the given polynomials. The remainders when p(x) and q(x) are divided by (x - 3) are p(3) and q(3) respectively.
By the given condition, we have
p(3) = q(3)
⇒ a×33+4×32+3×3−4=33−4×3+a
⇒ 27a+36+9−4=27−12+a
⇒ 26a+26=0
⇒ 26a=−26
⇒ a=−1