Question

9. If x2 – 4x = 1, find x2 +
1
x2​

Answer 1

Step-by-step explanation:

Solution,

Given, x^2 - 4x = 1

x^2 + 2 × 1 =?

We have

x^2 - 4x = 1

x ( x - 4) = 1

Or, (x + 2) ( x - 2) = 1

Hence the value of x may be 2 or - 2

Now, taking the value of x = 2

x^2 + 1 ×2 = 2 ^2 + 1 × 2

= 4 + 2

= 2

Now , taking the value of x = - 2

x^2 + 1 × 2 = (-2)^2 + 1 × 2

= 4 + 2

= 6