Question

(5) Write the following expressions using the summation notation.

x₁y₁ + x₂y₂ + x₃y₃ + x₄y₄

The following ``answers'' have been proposed for part (c).
(a) ∑⁴_i=1 x_iyi
(b) (∑⁴_i=1 x_i) (∑⁴_i=1 yi),
(c) ∑⁴_i=1 (x_i + yi),
(d) (∑⁴_i=1 x_i) + (∑⁴_i=1 yi),
(e) None of the above.

Answer 1

Here the following expressions with summation notation can be written as option a so option a is answer.