ab+bc+ca lies in.....?
plzzzz its urgent
thankssss in advance....
4 years, 5 months ago
i'm assuming the are all real. Using cauchy-schwarz inequality, we get;
\( (a^2+b^2+c^2)(b^2+c^2+a^2) \geq (ab+bc+ca)^2\)
\(1 \geq (ab+bc+ca)^2 \)
\( 1 \geq ab+bc+ca \geq -1\)
Now we could also use \( (a+b+c)^2 \geq 0\)
\( a^2+b^2+c^2+2(ab+bc+ca) \geq 0\)
\( ab+bc+ca \geq -0.5\)
So we get C.
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actually haven't read this theorem.......can you give me a link where it is written in easy and understandable manner....plzzzz
Here's a link with some proofs of it:http://rgmia.org/papers/v12e/Cauchy-Schwarzinequality.pdf
The second proof is pretty simple and easy... i think...
@Kee Wei Lee
ans is c
how did u got the answer?
Are u missing any information?