Step by Step Solution
Rearrange:
Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :
x^3-(1000000)=0
Step by step solution :
Step 1 :
Trying to factor as a Difference of Cubes:
1.1 Factoring: x3-1000000
Theory : A difference of two perfect cubes, a3 - b3 can be factored into
(a-b) • (a2 +ab +b2)
Proof : (a-b)•(a2+ab+b2) =
a3+a2b+ab2-ba2-b2a-b3 =
a3+(a2b-ba2)+(ab2-b2a)-b3 =
a3+0+0-b3 =
a3-b3
Check : 1 is not a cube !!
Ruling : Binomial can not be factored as the difference of two perfect cubes
Polynomial Roots Calculator :
1.2 Find roots (zeroes) of : F(x) = x3-1000000
Polynomial Roots Calculator is a set of methods aimed at finding values of x for which F(x)=0
Rational Roots Test is one of the above mentioned tools. It would only find Rational Roots that is numbers x which can be expressed as the quotient of two integers
The Rational Root Theorem states that if a polynomial zeroes for a rational number P/Q then P is a factor of the Trailing Constant and Q is a factor of the Leading Coefficient
In this case, the Leading Coefficient is 1 and the Trailing Constant is -1000000.
The factor(s) are:
of the Leading Coefficient : 1
of the Trailing Constant : 1 ,2 ,4 ,5 ,8 ,10 ,16 ,20 ,25 ,32 , etc
Let us test ....
| P | Q | P/Q | F(P/Q) | Divisor | |||||
|---|---|---|---|---|---|---|---|---|---|
| -1 | 1 | -1.00 | -1000001.00 | ||||||
| -2 | 1 | -2.00 | -1000008.00 | ||||||
| -4 | 1 | -4.00 | -1000064.00 | ||||||
| -5 | 1 | -5.00 | -1000125.00 | ||||||
| -8 | 1 | -8.00 | -1000512.00 |
Note - For tidiness, printing of 15 checks which found no root was suppressed
Polynomial Roots Calculator found no rational roots
Equation at the end of step 1 :
x3 - 1000000 = 0
Step 2 :
Solving a Single Variable Equation :
2.1 Solve : x3-1000000 = 0
Add 1000000 to both sides of the equation :
x3 = 1000000
When two things are equal, their cube roots are equal. Taking the cube root of the two sides of the equation we get:
x = ∛ 1000000
Can ∛ 1000000 be simplified ?
Yes! The prime factorization of 1000000 is
2•2•2•2•2•2•5•5•5•5•5•5
To be able to remove something from under the radical, there have to be 3 instances of it (because we are taking a cube i.e. cube root).
∛ 1000000 = ∛ 2•2•2•2•2•2•5•5•5•5•5•5 =2•2•5•5•∛ 1 =
100 • ∛ 1 =
100
The equation has one real solution
This solution is x = 100
One solution was found :
x = 100How did we do?
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