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$a + b = 7$ ഉം $a - b = 3$ ഉം ആണെങ്കിൽ, $a^2 - b^2$ എന്താണ്?

A$14$
B$10$
C$21$
D$28$
Answer & Solution
Correct answer: C. $21$
ചതുര വ്യത്യാസ ഐഡന്റിറ്റി $a^2 - b^2 = (a+b)(a-b) = 7 \times 3 = 21$ ഉപയോഗിക്കുക.
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