Question

Solve by completing the square: x^2 + 7x + 4 = 0

Answer 1

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.

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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

.

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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

Step-by-step explanation: