If |a|=|b| then (a+b).(a-b) is - Vidyadip

MCQ

If $ |a|=|b| $ then $ (a+b).(a-b) $ is

A
Positive
B
Negative
✓
Zero
D
None of these

✓

Answer

Correct option: C.

Zero

c
(c) $(a + b)\,\,(a - b) = a.a +b.a -b.a - b.b $

$ = a.a - b.b = \,|a{|^2} - |b{|^2}$

$ = 0$ $(\because \,|a|\, = \,|b|)$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

JEE STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

A bag contains $3$ red, $7$ white and $4$ black balls. If three balls are drawn from the bag, then the probability that all of them are of the same colour is

The function ${{a\sin x + b\cos x} \over {c\sin x + d\,\cos x}}$ is decreasing, if

If $\alpha , \beta , \gamma $ are roots of equation ${x^3} + a{x^2} + bx + c = 0$, then ${\alpha ^{ - 1}} + {\beta ^{ - 1}} + {\gamma ^{ - 1}} = $

The orthocentre of the triangle formed by the lines $xy = 0$ and $x + y = 1$ is

In the complex plane, let $z_1=\sqrt{3}+i$ and $z_2=\sqrt{3}-i$ be two adjacent vertices of an $n$-sided regular polygon centered at the origin. Then, $n$ equals

If $f(x) = \frac{{\sin \frac{{\pi x}}{4}}}{{x + 1}} ,$ then $\mathop {\lim }\limits_{h \to 0} \frac{{f(1 + h) - f(1)}}{{{h^2} + 2h}}$ is -

If $A = \{x : x$ is a multiple of $4\}$ and $B = \{x : x$ is a multiple of $6\}$ then $A \cap B$ consists of all multiples of

The approximate value of $(1.0002)^{3000}$ is

If $90^\circ < A < 180^\circ $ and $\sin A = \frac{4}{5},$ then $\tan \frac{A}{2}$ is equal to

Six cards are drawn simultaneously from a pack of playing cards. What is the probability that $3$ will be red and $3$ black