Solution - Linear equations with one unknown
Other Ways to Solve
Linear equations with one unknownStep 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-(105)=0
Step by step solution :
Step 1 :
Trying to factor as a Difference of Cubes:
1.1 Factoring: x3-105
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 : 105 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) = x3-105
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 -105.
The factor(s) are:
of the Leading Coefficient : 1
of the Trailing Constant : 1 ,3 ,5 ,7 ,15 ,21 ,35 ,105
Let us test ....
| P | Q | P/Q | F(P/Q) | Divisor | |||||
|---|---|---|---|---|---|---|---|---|---|
| -1 | 1 | -1.00 | -106.00 | ||||||
| -3 | 1 | -3.00 | -132.00 | ||||||
| -5 | 1 | -5.00 | -230.00 | ||||||
| -7 | 1 | -7.00 | -448.00 | ||||||
| -15 | 1 | -15.00 | -3480.00 | ||||||
| -21 | 1 | -21.00 | -9366.00 | ||||||
| -35 | 1 | -35.00 | -42980.00 | ||||||
| -105 | 1 | -105.00 | -1157730.00 | ||||||
| 1 | 1 | 1.00 | -104.00 | ||||||
| 3 | 1 | 3.00 | -78.00 | ||||||
| 5 | 1 | 5.00 | 20.00 | ||||||
| 7 | 1 | 7.00 | 238.00 | ||||||
| 15 | 1 | 15.00 | 3270.00 | ||||||
| 21 | 1 | 21.00 | 9156.00 | ||||||
| 35 | 1 | 35.00 | 42770.00 | ||||||
| 105 | 1 | 105.00 | 1157520.00 |
Polynomial Roots Calculator found no rational roots
Equation at the end of step 1 :
x3 - 105 = 0
Step 2 :
Solving a Single Variable Equation :
2.1 Solve : x3-105 = 0
Add 105 to both sides of the equation :
x3 = 105
When two things are equal, their cube roots are equal. Taking the cube root of the two sides of the equation we get:
x = ∛ 105
The equation has one real solution
This solution is x = ∛105 = 4.7177
One solution was found :
x = ∛105 = 4.7177How did we do?
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