Question

if 4x2-6x+1=0 then what is value of 8x3+(8x3)-1​

Answer 1

Answer:

 It helps if you properly identify denominators. We presume your expressions are 

.. x + 1/(4x) = 3/2 

.. 8x^3 + 1/(8x^3) 

Multiply the first by 4x and subtract 6x to get a quadratic: 

.. 4x^2 - 6x + 1 = 0 

This has solutions 

.. x = (3 ± √5)/4 

Recognize the second expression is 

.. y + 1/y 

where 

.. y = (2x)^3 

You know that 

.. (a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^3 

so 

.. y = (2x)^3 = (1/8)(3^3 ± 3(3^2)(√5) + 3(3)(5) ± 5√5) 

.. = (1/8)(27 ± 27√5 + 45 ± 5√5) 

.. = 9 ± 4√5 

and 

.. y + 1/y = (9 ± 4√5) + 1/(9 ± 4√5) 

.. = 9 ± 4√5 + (9 ∓ 4√5)/(9^2 - 4^2*5) ... rationalize the denominator (=1) 

.. = 9 ± 4√5 + 9 ∓ 4√5 ... root 5 terms cancel 

.. = 18

Answer 2

Step-by-step explanation:

4x2 -6x+1=0

8-6x+1=0

8-6x=-1

6x = -1-8

6x = -9

x= -9/-6

x= 3/2 ------>>> is the answer

HOPE IT HELPS YOU ..... :)