Question

solve by completing square method 2x²-3x-9=0​

Answer 1

✪AnSwEr

${\tt{\red{\underline{\large{Given}}}}}$

• A equation
• 2x²-3x-9=0

${\sf{\green{\underline{\large{To\:find}}}}}$

• Factors of given quadratic equation
• By completing squaring method

${\sf{\pink{\underline{\Large{Explanation}}}}}$

2x²-3x-9=0

Multiplying by 2

=>4x²-6x-18=0

=>(2x)²-2×2x × 3/2 +(3/2)² -(3/2)² -18 =0

=>(2x-3/2)²=18+9/4

=>(2x-3/2)²=81/4

=>(2x-3/2)=$\pm\sqrt{\frac{81}{4}}$

Taking x as +

=>(2x-3/2)=$+\sqrt{\frac{81}{4}$

=>2x=$+\frac{3}{2}+{\frac{9}{2}}$

=>x=$\dfrac{1}{2}(\frac{3}{2}+\frac{{9}{2}})$

=>x=$\dfrac{1}{2}(\frac{12}{2}$

=>3

Taking x as -

=>(2x-3/2)=$-\sqrt{\frac{81}{4}$

=>2x=$+\frac{3}{2}-{\frac{9}{2}}$

=>x=$\dfrac{1}{2}(\frac{3}{2}-\frac{{9}{2}})$

=>x=$\dfrac{1}{2}(\frac{-6}{2}$

=>-3/2