54,195 views
38 votes
38 votes
What is the value of x for 3x^2 - x + 9 = 0

User Eetawil
by
2.7k points

2 Answers

23 votes
23 votes
1 Use the Quadratic Formula.
1 In general, given
a
x
2
+
b
x
+
c
=
0
ax
2
+bx+c=0, there exists two solutions where:
x
=

b
+
b
2

4
a
c
2
a
,

b

b
2

4
a
c
2
a
x=
2a
−b+
b
2
−4ac



,
2a
−b−
b
2
−4ac





2 In this case,
a
=
3
a=3,
b
=

1
b=−1 and
c
=
9
c=9.
x
=
1
+
(

1
)
2

4
×
3
×
9
2
×
3
,
1

(

1
)
2

4
×
3
×
9
2
×
3
x
=
2×3
1+
(−1)
2
−4×3×9



,
2×3
1−
(−1)
2
−4×3×9





3 Simplify.
x
=
1
+
107
ı
6
,
1

107
ı
6
x=
6
1+
107



,
6
1−
107





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x
=
1
+
107
ı
6
,
1

107
ı
6
x=
6
1+
107



,
6
1−
107



User Sachin Yadav
by
2.5k points
14 votes
14 votes

Correct option is A)

Consider the given equation,

3

2x

+10.3

x

−9=0

Let ,y=3

x

Now ,

y

2

−10y+9=0

y

2

−9y−y+9=0

y(y−9)−1(y−9)=0

(y−9)(y−1)=0

When,

x−9=0

x=9

Now ,

9=3

x

3

2

=3

x

x=2

When,

y−1=0

y=1

3

x

=1

3

x

=3

0

x=0

x=0,x=2

This is the answer

User Heinrich Lee Yu
by
2.7k points
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