Question

If a=2-√5÷2+√5 and b=2+√5÷2-5, Find a²-b² a) -144√5 b) 144 √5 c) 81√5 d) -81√5 ​

Answer 1

Answer:

a=(2-√5)/(2+√5)

b=(2+√5)/(2-√5)

a+b=(2-√5)/(2+√5)+(2+√5)/(2-√5)

={(2-√5)^2+(2+√5)^2}/(2+√5)(2-√5)

=(4+5-4√5+4+5+4√5)/(2^2-√5^2)

=18/(4-5)

=18/-1

= -18

again ,

a-b=(2-√5)/(2+√5)-(2+√5)/(2-√5)

={(2-√5)^2-(2+√5)^2}/(2+√5)(2-√5)

=(4+5-4√5-4-5-4√5)/(2^2-√5^2)

=(-8√5)/(4-5)

= -8√5/-1

=8√5

a^2-b^2

=(a+b)(a-b)

= -18×8√5

= -144√5

so ( a ) is the correct answer

Answer 2

Answer:

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Step-by-step explanation:

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