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QUESTION: Dear Sir, please help me. Thank you. These is a question about summation. Thank you.
)
ANSWER: Hello Josephine,
The ∑ is only a summing indicator to tell us what to sum & till when .
3
∑ 3x(i) = 3x(1)+3x(2)+3x(3) = 3*6+3*3+3*7 = 48 .
i=1
Alon.
---------- FOLLOW-UP ----------
QUESTION: Thank you so much for the help sir. May I ask for another one? How do I write this in summation? x3+x4+X5+x6? I also have another one in the image. Thank you so much.
)
(a)
x3+x4+X5+x6 =
6
∑ xi
i=3
(b)
5
∑ x(i)y(ii) = x(1)y(11)+x(2)y(22)+x(3)y(33)+x(4)y(44)+x(5)y(55) .
i=1
Its important to notice that y(11) is an index of a matrix ("colom 1 , row 1") while x(1)
is 1 dimensional vector !!
Alon.
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Answers by Expert:
Alon Mandes
Expertise
Kind of questions I can answer : Limits, Derivatives, Integration, Implicit functions, continuousity, differentiation ,Extremum problems, Lagrange multipliers, Gradients, Surface integrals, Multi variables functions ,Multi variables Integrals,Complex variables ,Complex functions, Curves, Trajectory integrals & Vector analyse,Divergence,Rotor & word problems. Kind of question I can't answer : Economics,Combinatorics,infinite series & convergence ,Statistics & Probabilities .
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1. I'm a team member of mathnerds (math site for answering questions)
2. I'm a team member in the Student's Union of the Technion, helping
students who have problems in mathematics.
3. 2 years of experience as a math teacher in college.
4. I give free homework help for high school students in
Mathematics & Physics.
5. I teach part time in collage the subjects : "Digital Signal Processing" , "Random Signals & Noise" ,
"Complex Functions".
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M.A in Mathematics & Bs.c in Electronics.
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