algebra

solve for x

1) (x2+2)2 + 8x2 = 6x (x2+2)

11 Answers

341
Hari Shankar ·

doesnt this belong to IX-Xth sub-forum?

62
Lokesh Verma ·

the observation would have been to divide by x^2

\left(x+2/x \right)^2+8=6(x+2/x)

Lets put x+2/x= t

then you have a quadratic in t which solves to t=2 or 4

now solve... for x+2/x=2 or x+2/x = 4

1
Sonne ·

@ ^ wow

1
jangra28192manoj jangra ·

thats nice

6
AKHIL ·

gr88 nishant sir!!!!

1
जय ·

i have another one ... a bit lenGthy

(x^2 + 2) ( x^2-6x +2) = - 8 x^2

\textrm{now \: dividing \, by } x^2( x≠0)

\left ( x +\frac{2}{x} \right )\left ( x + \frac{2}{x} -6 \right ) = - 8

let

x +\frac{2}{x} = t

the equation becomes

\left ( t \right )\left ( t-6 \right ) = -8

t^2 - 6t + 8 = 0

\left ( t-4 \right )\left ( t-2 \right ) = 0

\boxed {t=4}\, \, \textrm{ AND} \, \boxed {t=2}

solvin we have

\boxed{x = 1\pm i}
and
\boxed{x = 2\pm \sqrt{2}}

ricky has explained in detail below abt x≠0

62
Lokesh Verma ·

what you have done is not at all different from the original question...

take (x2+2)(x2+2-6x)=-8x2

= (x2+2)(x2+2)-8x2=6x(x2+2)

which isthe original question [3]

1
जय ·

yes sir .........but isn't it a method of rearrangement for sake of convenience of solving basic problem....doesn't it help in simplification.....[60]

62
Lokesh Verma ·

oh! sorry i din notice that you were giving a solution :D sorry i thought it was another problem :D

1
Ricky ·

I would just like to add that we are allowed to divide by " x 2 " because x = 0 doesn ' t

satisfy the equation .

1
जय ·

thnks ricky ( btw had mentioned it in hidden box)

HAPPY BIRTHDAY @ ricky [96][69][70][76]

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