1.

निम्नलिखित सम्मिश्र संख्याओं `x+iy` को के रूप में निरूपित कीजिए । (i) `(2-sqrt(-25))/(1-sqrt(-16))` (ii) `(5+2i)/(-1+sqrt(3i))` (iii) `(sqrt(5)-7i)(sqrt(5)-7i)^(2)+(-2+7i)^(2)`

Answer» (i) `(2-sqrt(-25))/(1-sqrt(-16))=(2-5i)/(1-4i)=(2-5i)/(1-4i)xx(1+4i)/(1+4i)`
`=(2+8i-5i-20i^(2))/(1-16i^(2))`
`=(2+3i-20(-1))/(1-16(-1))`
`=(2+3i+20)/(1+16)`
`=(22+3i)/(17)=(22)/(17)+(3)/(17)i`
(ii) `(5+2i)/(-1+sqrt(3)i)=(5+2i)/(-1+sqrt(3)i)xx(-1-sqrt(3)i)/(-1-sqrt(3)i)`
`=(-5-5sqrt(3)i-i-2sqrt(3)*i^(2))/((-1)^(2)-(sqrt(3)i)^(2))`
`=(-5-5sqrt(3)i-2i-2sqrt(3)(-1))/(1-3(-1))`
`=((-5+2sqrt(3))+(-5sqrt(3)-2)i)/(1+3)`
`=((-5+2sqrt(3))/(4))+((-5sqrt(3)-2)/(4))i`
(iii) `(sqrt(5)-7i)(sqrt(5)-7i)^(2)+(-2+7i)^(2)=(sqrt(5)-7i)^(3)+(-2+7i)^(2)`
`=5sqrt(5)-3(sqrt(5)^(2))(7i)+3(sqrt(5))(7i)^(2)-(7i)^(3)+(4-28i+49i^(2))`
`=(5sqrt(5)-105i+147sqrt(5)i^(2)-343i^(3))+(4-28i-49)`
`=(5sqrt(5)-105i-147sqrt(5)+343i)+(-45-28i)`
`=(5sqrt(5)-147sqrt(5)-45)+i(-105+343-28)`
`=-(142sqrt(5)+45)+(210)i`


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