If two of the zeros of the cubic polynomial ax3 + bx2 + cx + d are each equal to zero, then the third zero is
Given,
ax3 + bx2 + cx + d
By Putting x = 0
0 + d = 0
d = 0
ax3 + bx2 + cx + d = 0
x(ax2 + bx + c) = 0
Put x = 0
c = 0
ax2 + bx = 0
x(ax + b) = 0
Hence,
x = – b/a