What is the answer to the expression when factoring it over the complex numbers?

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Answer 1 · 2017-10-23T16:39:07

#(y+7i)(y-7i)#

we use

(i) the difference of squares

#color(red)(x^2-y^2=(x+y)(x-y))#

and

(ii) using the fact that

#color(red)(i^2=-1)#

#y^2+49=y^2-(-49)#

#=(y+7i)(y-7i)#