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Question
For what value of x would this expression be a perfect square: $6.16 × 6.16 - x × 6.16 + 0.3 × 0.3$?
A
0.6.
B
0.06.
C
0.0006.
D
6.0.
Soln.
Ans: a
Ans: a
Comparing the given expression with $a^2 - 2 × a ×b + b^2 = (a - b)^2$, we see that if a = 6.16, and b = 0.3 then by inspection, x should be equal to 2b = 2 × 0.3 = 0.6.