How to solve the equation 4x ^ 4-29x ^ 3 + 39 ^ 2 + 32x-10 = 0 Whether we can solve it without Descartes or Ferrari's method is not easy

How to solve the equation 4x ^ 4-29x ^ 3 + 39 ^ 2 + 32x-10 = 0 Whether we can solve it without Descartes or Ferrari's method is not easy

If u / V is the rational root of the equation 4x ^ 4-29x ^ 3 + 39x ^ 2 + 32x-10 = 0, then u is the factor of the constant 10, V is the factor of the coefficient 4 of the higher order term, and x = 5 and 1 / 4 are the roots of the equation through the test. Then decompose the factor, from above, there must be the factor (4x-1) (X-5) = 4x ^ 2-21x + 5, ∵

4 / 5 of a number is more than 20% of 120. 24 equations!

Let the number be x, then we can get it according to the meaning of the question
4/5x-120*20%=24
The solution is x = 60

The seller sells two fifths of the original color TV sets, and has 120 sets. Now the number is four fifths less than the original. How many original color TV sets should be solved by the equation
The current price of the tape recorder is 368 yuan, which is 2 / 25 lower than the original price. How much is the reduction per set

There are x original color TV sets
（1-2/5）x-4/15x=120
6/15x-4/15x=120
2/15x=120
x=900
368÷（1-2/25）-368
＝368÷23/25-368
＝400-368
= 32 yuan

Three fifths of a number is 30 less than 120. Solve the number equation,

Let this number be X
3x/5=120-30
x=150