51.5k views
5 votes
Solve by completing the square:
x^2 + 7x + 4 = 0

User Modesta
by
5.4k points

2 Answers

6 votes

Answer: x= -1 ±√113/14

User Lorenzo Isidori
by
4.6k points
1 vote

Answer:

x

2

+

7

x

4

=

0

Add

4

to both sides of the equation.

x

2

+

7

x

=

4

To create a trinomial square on the left side of the equation, find a value that is equal to the square of half of

b

.

(

b

2

)

2

=

(

7

2

)

2

Add the term to each side of the equation.

x

2

+

7

x

+

(

7

2

)

2

=

4

+

(

7

2

)

2

Simplify the equation.

Tap for more steps...

x

2

+

7

x

+

49

4

=

65

4

Factor the perfect trinomial square into

(

x

+

7

2

)

2

.

(

x

+

7

2

)

2

=

65

4

Solve the equation for

x

.

Tap for more steps...

x

=

±

65

2

7

2

The result can be shown in multiple forms.

Exact Form:

x

=

±

65

2

7

2

Decimal Form:

x

=

0.53112887

7.53112887

Explanation:

User Edan Maor
by
4.8k points
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