Qualification > Math

C3 and C4 DOUBTS HERE!!!

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astarmathsandphysics:
Complete the square for the numerator to get (x+1/2)^2+3/4>=3/4

Aadeez || Zafar:
b)

let x2+x+1 be equal to y
y = x2+x+1
  = x2+x+.25+.75
 = (x+.5)2+.75
 
there fore (x+.5)2 is a positive number and so .75 added to positive number gives positive number

and so

y is positive
therefore y>0
=x2+x+1>0

C)2+x+1 is positive and (x+2)2 is positive so positve number divided by positive is positive and so f(x) is positive

so therefor f(x)>0

**RoRo**:

--- Quote from: Mr. MUST on April 30, 2011, 10:08:06 am ---b)

let x2+x+1 be equal to y
y = x2+x+1
  = x2+x+.25+.75
 = (x+.5)2+.75
 
there fore (x+.5)2 is a positive number and so .75 added to positive number gives positive number

and so

y is positive
therefore y>0
=x2+x+1>0

C)2+x+1 is positive and (x+2)2 is positive so positve number divided by positive is positive and so f(x) is positive

so therefor f(x)>0

--- End quote ---

Okay, thank you very much! :D

Blizz_rb93:
f(x) = x + 3/x-1 - 12/x^2 + 2x -3  [x is an element of all eral number, x>1]

Show that f(x) = x^2 + 3x + 3 / x+3

in the book page 11 mixed exercise 1e q4

Thank you

thenewkid™:
anybody have any revision notes or pointers?

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