Rewrite the following expression in the form a Squareroot b
Solution
4) a )
(x+3) / ( 4x^2 - 9 ) divide by (x^2+7x+12) / ( 2x^2 - 7x + 3)
factoring each polynomial
4x^2 - 9 = (2x-3) (2x+3)
x^2 + 7x + 12 = (x+4)(x+3)
2x^2 -7x + 3 = (2x-1)(x-3)
hence the rational expression now becomes
(x+3) / (2x-3) (2x+3) divide by (x+4)(x+3) / (2x-1)(x-3)
(x+3) / (2x-3) (2x+3) * (2x-1)(x-3) / (x+4)(x+3)
(2x-1)(x-3) / ( 2x-3)(2x+3)(x+4)
b) { x / (x^2 + x- 2) } - {2 / ( x^2 - 5x + 4) }
factors of x^2 + x - 2 = (x+2)(x-1)
factors of x^2-5x+4 = (x-1)(x-4)
therefore lcd is (x+2)(x-1) (x-4)
{x (x-4) - 2 ( x+2) } / (x+2)(x-1) (x-4)
x^2 - 4x -2x - 4 / (x+2)(x-1) (x-4)
(x^2 -6x - 4 ) / (x+2)(x-1) (x-4)
5) general solution of ax^2 + bx + c = 0
x = {-b + - sqrt ( b^2 - 4ac ) } / 2a
x^2 + 1 = 4x
subtracting 4x from both sides
x^2 - 4x + 1 = 0
a = 1 , b = -4 , c = 1
plugging the values of a,b,c in the quadratic formula
x = {- ( -4) + - sqrt ( (-4)^2 - 4* 1* 1 }/ 2* 1
x = { 4 + - sqrt 12 } / 2
x1 = 2+ sqrt 3
x2 = 2 - sqrt 3

