Question

Consider the quadratic equation x2+8x+9=0. Which of the following is the correct form after substituting a, b, and c into the Quadratic Formula?

Answer 1

As given

• x²+8x+9=0

General equation

• Ax²+Bx+C

On comparing

• A=1
• B=8
• C=9

Answer 2

x²+8x+9=0

Comparing above equation with ax²+bx +c

we get

a=1

b=8

c=9

quadratic equation is

`x = \frac{ - 8± \sqrt{ {8}^(2) - 4×1×9} }{2*1}`

`x = ( -8± √( 64-36) )/(2)`

2x+8=±
`\sqrt{ {28}}`

taking + ve

2x=
`\sqrt{ {28}}`-8

x=
`2\sqrt{ {7}}`-8/2

x=
`\sqrt{ {7}}`-4

taking -ve

2x=-
`\sqrt{ {28}}`-8

x=-
`2\sqrt{ {7}}`-8/2

x=-
`\sqrt{ {7}}`-4