Question

Hey guys- need help in this one

Answer 1

c

Explanation:

given x = 5 + i
`√(7)` then y = 5 - i
`√(7)`

x² - 2xy + y² ← is a perfect square

= (x - y)² ← substitute values for x and y

= (5 + i
`√(7)` - (5 - i
`√(7)` )²

= (5 + i
`√(7)` - 5 + i
`√(7)` )²

= (2i
`√(7)` )²

= 2² × i² × (
`√(7)` )²

= 4 × - 1 × 7

= - 28

Answer 2

c

Explanation:

`x=5+i√(7) , y = 5-i√(7)\\ x^2-2xy+y^2=(x-y)^2\\ (x-y)^2=(2i√(7) )^2\\4.i^2.7\\-28`