Question

If x2 + 4x – 1 = 0 (x > 0), find the value of the following:
(ii) x² +
x2
(i) x + 1
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Answer 1

Answer:

x

2

−4x+1=0

D=b

2

−4ac=16+4=20

x=

2a

−b±

D

=

2

4±2

5

=2±

5

now

x

3

x

3

−1

=(x−

x

1

)

3

−3(x−

x

−1

)

now x−

x

1

=2+

5

−

2+

5

1

=

2+

5

(2+

5

)

2

−1

=

2+

5

9+4

5

−1

=4

then, x

3

x

3

−1

=(4)

3

−3(4)=4[16−3]=13×4

x

3

−

x

3

1

=52.

Answer 2

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