Question

If x square +2x =3 by using formula

Answer 1

CORRECT QUESTION:

x² + 2x = 3 Find the value of x

ANSWER:

Simplying we get

x² + 2x - 3 = 0

Now it is a quadratic equation

We can solve this in two methods

Method 1 : Using quadratic equation formula

Method 2 : Using factorisation

METHOD 1:

$\small{ \rm{ \implies x = \dfrac{ - b \pm \sqrt{ {b}^{2} - 4ac } }{2a} }}$

Here

a = 1 , b = 2 , c = -3

$\to \small{ \rm{x = \frac{ - 2 \pm \sqrt{ {2}^{2} - 4(1)( - 3) } }{2(1)} }}$

$\small{ \rm{\to x = \frac{ - 2 \pm \sqrt{4 + 12} }{2} }}$

$\to{ \rm{x = \frac{ - 2 \pm\sqrt{ {4}^{ \cancel2} } }{2} = \frac{ - 2 \pm (4)}{2} }}$

$\small{ \rm{ \to x = \frac{ - 2 + 4}{2} }(or) \frac{ - 2 - 4}{2} }$

${ \rm{ \to x = \frac{2}{2}(or) \frac{ - 6}{2} }}$

${ \rm{ \to x = 1(or) - 3}}$

METHOD 2:

x² + 2x - 3 = 0

Split the middle term

x² + 3x - x - 3 = 0

x(x + 3) - 1(x + 3) = 0

Taking common

(x + 3)(x - 1) = 0

x = -3 (or) 1

Hence x = -3 or 1