Problem: The smaller root of the equation (x−43)(x−43)+(x−43)(x−21)=0 is:
Answer Choices:
A. −43
B. 21
C. 85
D. 43
E. 1
Solution:
We can re-write the equation as (x−43)[(x−43)+(x−21)]=0
∴(x−43)(2x−45)=0,x=43 or x=85. Since 85<43, the correct answer is (C).