29-7-10 Quadratic Equation....

Solve: x2+9x2(x+3)2=16

3 Answers

1
जय ·

x+ 3= y

eqn is
(y-3)^2 + \frac{9 ( y-3)^2}{y^2} = 16
(y-3)^2(y^2+9)= 16y^2

(y^2-6y+9)(y^2+9)= 16y^2

original :-
\frac{(y^2-6y+9)(y^2+9)}{y ( y) }= 16y^2

edit:- ON ADVICE OF NISHANT BHAIYYA

\frac{(y^2-6y+9)(y^2+9)}{y ( y) }= 16

\left ( y + \frac{9}{y} -6 \right )(y +\frac{9}{y}) =16

y + \frac{9}{y} = t\rightarrow (t-6)(t)= 16 \rightarrow t^2-6t-16 =0

we have
\boxed {t=8 } \, and \, \, \boxed{t=2}

we have
\boxed {y=4 \pm \sqrt{7}} \, and \, \, \boxed{y= -1 +i(2\sqrt{2})}

\boxed {x=1\pm \sqrt{7}} \, and \, \, \boxed{x= -4 \pm i(2\sqrt{2})}

62
Lokesh Verma ·

Very good work, except that at one steop you missed out dividing the RHS by y^2... but subsequently corrected that [1]

23
qwerty ·

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