find the value of 6x^3 + x^2 - 7x + 2014 if 2x^2 + x =2
Let the answer = A, then
(1) 6x³ + x² - 7x + 2014 = A
Get 0 on the right of the given equation:
(2) 2x² + x - 2 = 0
Multiply (2) by -3x so that it will have a
cube term that will cancel the cube term of (1)
if we add them:
(3) -6x³ - 3x² - 6x = 0
Now add equations (1) and (3)
(1) 6x³ + x² - 7x + 2014 = A
(3) -6x³ - 3x² - 6x = 0
-------------------------------
(4) -2x² - x + 2014 = A
Now add equations (4) and (2)
(4) -2x² - x + 2014 = A
(2) 2x² + x - 2 = 0
-----------------------
2012 = A
The answer is 2012.
Edwin