Question

By completing the square method 3x2+2root5-5

Answer 1

Answer:

Given 3x

2

−5x+2=0

Here, the coefficient of x

2

is 3 and it is not a perfect square.

∴ Multiply the equation throughout by 3.

⇒(3x

2

−5x+2=0)×3∴9x

2

−15x+6=0

Now, half of the coefficient of x is

2

5

.∴b=

2

5

and b

2

=(

2

5

)

2

So, 9x

2

−15x+(

2

5

)

2

−(

2

5

)

2

+6=0,(3x)

2

−15x+(

2

5

)

2

=(

2

5

)

2

−6

(3x−

2

5

)

2

=

4

25

−6=

4

1

(Taking square root on both the sides)

∴3x−

2

5

=±

2

1

∴3x−

2

5

=±

2

1

or 3x−

2

5

=−

2

1

3x=

2

1

+

2

5

3x=

2

5

−

2

1

3x=

2

6

=3 3x=

2

4

=2

∴x=1 x=

3

2