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Last updated at Jan. 19, 2019 by Teachoo
Transcript
Ex 5.1, 10 Express the given Complex number in the form a + ib: (โ2โ1/3 ๐)^3 (โ2โ1/3 ๐)^3 = โ 1 (2+1/3 ๐)^3 = โ (2+1/3 ๐)^3 It is of the form (a + b)3 Using (a + b)3 = a3 + b3 + 3 ab (a + b) Here a = 2 and b = 1/3 i = โ((2)^3+(1/3 ๐)^3+3 ร2ร1/3 ๐(2+1/3 ๐)) = โ(8+(1/3)^3ร(๐)^3+2๐(2+1/3 ๐)) = โ(8+1/27 ๐^3+4๐+2/3 ๐^2 ) = โ(8+1/27 ใ๐ร๐ใ^2+4๐+2/3 ๐^2 ) Putting ๐^2=โ1 = โ1 (8+1/27 ๐(โ1)+4๐+2/3 (โ1)) = โ1 (8โ1/27 ๐+4๐โ2/3) = โ 8 + 1/27 ๐ โ 4i + 2/3 = โ 8 + 2/3 + ( 1)/27 ๐ โ 4๐ = (โ 8+ 2/3) + (( 1)/27โ4)๐ = ((โ24 + 2)/3) + ((1 โ 4 ร27)/27)๐ = (โ22)/3 + ((1 โ108)/27)๐ = (โ22)/3 + (( โ107)/27)๐ = (โ22)/3 โ ( 107)/27 ๐
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