If x = (5 + 331/2)/4 then find the value of 8x3 + 6x2 - 69x + 20 ?1. -

1.	If x = (5 + 331/2)/4 then find the value of 8x3 + 6x2 - 69x + 20 ?1. -332. +333. 04. 1
Answer» Correct Answer - Option 2 : +33 Given: x = (5 + 33^1/2)/4 Calculation: 4x - 5 = 33^1/2 Squaring both sides we get, 16x² + 25 - 40x = 33 16x² -40x - 8 = 0 2x² - 5x - 1 = 0 ----(1) To find: The value of 8x³ + 6x² -69x + 20 = ? Calculation: Taking eq(1) and multiplying it by some factors to get the evaluating part. firstly we will multiply eq(1) by 4x in order to get the first term of evaluating part (8x³) then we will multiply the 13. 4x (2x² - 5x - 1) + 13 (2x² - 5x - 1) = 0 On solving and addition and subtraction of 20 above we get, 8x³ + 6x² -69x -13 + 20 - 20 =0 8x³ + 6x² -69x + 20 = 33

If x = (5 + 331/2)/4 then find the value of 8x3 + 6x2 - 69x + 20 ?1. -332. +333. 04. 1

Answer» Correct Answer - Option 2 : +33

Given:

x = (5 + 33^1/2)/4

Calculation:

4x - 5 = 33^1/2

Squaring both sides we get,

16x² + 25 - 40x = 33

16x² -40x - 8 = 0

2x² - 5x - 1 = 0 ----(1)

To find:

The value of 8x³ + 6x² -69x + 20 = ?

Calculation:

Taking eq(1) and multiplying it by some factors to get the evaluating part. firstly we will multiply eq(1) by 4x in order to get the first term of evaluating part (8x³) then we will multiply the 13.

4x (2x² - 5x - 1) + 13 (2x² - 5x - 1) = 0

On solving and addition and subtraction of 20 above we get,

8x³ + 6x² -69x -13 + 20 - 20 =0

8x³ + 6x² -69x + 20 = 33

Discussion

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