SOLUTION: what is the value of x when xcube + 3x = 47 The question says that it has a solution between 3 and 4. what does this mean. what should i take the value of a? i have got the an

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: what is the value of x when xcube + 3x = 47 The question says that it has a solution between 3 and 4. what does this mean. what should i take the value of a? i have got the an      Log On


   



Question 137100: what is the value of x when
xcube + 3x = 47
The question says that it has a solution between 3 and 4. what does this mean.
what should i take the value of a?
i have got the answer 5.52 and -8.52. is it right
What would happen if the question was like below
4xcube + 3x=20
what should i take the value of a is it 4?? and what should i do with the cube? does it affects the formula

Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
cube means raised to the power of 3. So yes, cube really affects the problem.
Let's look at the first one.
Given: x%5E3+%2B+3x+=+47 show the value is between 3 and 4.
Substitute in x = 3
3%5E3+%2B+3%2A3 = 27%2B9 = 36 which is less than 47
Now use 4
4%5E3+%2B+4%2A3 = 64%2B12 = 76 which greater than 47. So x lies beween 3 and 4.
Make sense?