Question

3x^2 +2x-7=0 solve by formula method
​

Answer 1

Answer:

Our equation is of the form

a

x

2

+

b

x

+

c

=

0

, therefore, we can use the quadratic formula. The quadratic formula is

x

=

−

b

±

√

D

2

a

, with

D

=

b

2

−

4

a

c

. We see that

a

=

3

,

b

=

−

2

and

c

=

7

.

Firstly, we calculate

D

.

D

=

b

2

−

4

a

c

=

(

−

2

)

2

−

4

⋅

3

⋅

7

=

−

80

. Because D is less than zero, there are no real roots. We can however calculate the imaginary solutions. We just calculate

x

:

x

=

−

b

±

√

D

2

a

=

2

±

√

−

80

2

⋅

3

=

2

±

√

−

1

⋅

√

16

⋅

√

5

6

=

2

±

i

⋅

4

√

5

6

=

1

3

±

2

3

i

√

5