Start learning →

यदि $a + b = 7$ और $a - b = 3$ है, तो $a^2 - b^2$ का मान क्या है?

A$14$
B$10$
C$21$
D$28$
Answer & Solution
Correct answer: C. $21$
वर्गों के अंतर की सर्वसमिका $a^2 - b^2 = (a+b)(a-b) = 7 \times 3 = 21$ का उपयोग करें।
Practise this question with Quill — RRB NTPC →

Keep practising Elementary Algebra

Browse all Elementary Algebra questions for RRB NTPC, or explore more Quantitative Reasoning topics.

Start a Elementary Algebra lesson →
Related questions
If $a + b + c = 6$ and $a^2 + b^2 + c^2 = 14$, find $ab + bc + ca$.If $x + \dfrac{1}{x} = 5$, find $x^3 + \dfrac{1}{x^3}$.Factorise $a^3 - b^3$.If $a + b + c = 0$, what is the value of $a^3 + b^3 + c^3$?Expand $(x + 5)^2$.