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math doubts [NEW]

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Ghost Of Highbury:
how sir?

9 - (x-3)2 is correct right?

(i edited it now)

(x+3)^2 - 9 doesnt give 6x - x^2

slvri:

--- Quote from: Z.J. on September 26, 2009, 05:36:28 pm ---18/x4 + 1/x2 =4
multiply by x4
18+x2=4x4
4x4-x2-18=0
4(x2)2-x2-18=0
u can see that this is a quadratic equation in x2
factorising we have
4x4-9x2+8x2-18=0
x2(4x2-9)+2(4x2-9)=0
4(x2-9)(x2+2)=0
either 4x2-9=0 or x2+2=0
4x2=9 or x2=-2
x2=9/4 (x2=-2 has no real roots, complex roots are +-sqrt(2)i)
so from the first one
x=sqrt(9/4)
x=+-(3/2)





the ones in red i didnt get it....plz elaborate... :-\
y is 4x2-9=0? wont it be x2-9=0?

--- End quote ---
sory i made a mistake there
and for the first one, u multiply each term in the equation by x^4 to turn it into a expression that u can factorise easily

zara:

--- Quote from: slvri on September 26, 2009, 08:12:11 pm ---sory i made a mistake there
and for the first one, u multiply each term in the equation by x^4 to turn it into a expression that u can factorise easily

--- End quote ---
yea Thanks...adi expalined it...=)

slvri:

--- Quote from: Z.J. on September 26, 2009, 08:14:59 pm ---yea Thanks...adi expalined it...=)



--- End quote ---
i hope u understood :)

zara:
yes slvri i did!

okay one more ques...

function f and g are defined by:
f(x): k-x    k is a constant
g(x): 9/x+2   whr x nt = 2   both x E R

Find the values of k for whch the eqtn f(x)=g(x) has two equal roots and solve the equation f(x)=g(x) in these cases.

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