Thursday 14 February 2013

Lesson Summary 14/2/13 Ryan Tan

Surds

Important = *

*
(2√3)^2
=2√3 x 2√3
=4√3√3
=4(√3)^2
=4(3)
=12

Conjugate Surds

*
(a+b)(a-b) = a^2 - b^2
(√a+√b)(√a-√b)=(√a)^2-(√b)^2
(a^1/2 + b^1/2) (a^1/2 - b^1/2) = (a^1/2)^2 - (b^1/2)^2

2√3^2=
a) 2√3 √3 (correct)
b)2(√3)^2 (correct)
c)2 . 3^1/2x2 (correct)
d) 4(3) (wrong)
e) √4(3) ^2 (wrong)
f) √4 √9 (wrong)


To convert irrational surds into rational surds

By similar surd
1/√2 x √2(to both numerator and denominator)
= √2 /2

By conjugate surd
(1/ √3 - √2) x √3 + √2 (to both numerator and denominator)
=√3 + √2/ 3-2
=√3 + √2 / 1


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