Problem: The roots of x(x2+8x+16)(4−x)=0 are
Answer Choices:
A. 0
B. 0,4
C. 0,4,−4
D. 0,4,−4,−4
E. none of these
Solution:
Set each factor equal to zero, and solve the three resulting equations. The roots are 0,−4,−4, and 4. (The factor x2+8x+16=(x+4)2 has the double root −4.)