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).