solve this r^2+2r-1 = 0
Answers
Step-by-step explanation:
Simplifying
r2 + 2r + -1 = 0
Reorder the terms:
-1 + 2r + r2 = 0
Solving
-1 + 2r + r2 = 0
Solving for variable 'r'.
Begin completing the square.
Move the constant term to the right:
Add '1' to each side of the equation.
-1 + 2r + 1 + r2 = 0 + 1
Reorder the terms:
-1 + 1 + 2r + r2 = 0 + 1
Combine like terms: -1 + 1 = 0
0 + 2r + r2 = 0 + 1
2r + r2 = 0 + 1
Combine like terms: 0 + 1 = 1
2r + r2 = 1
The r term is 2r. Take half its coefficient (1).
Square it (1) and add it to both sides.
Add '1' to each side of the equation.
2r + 1 + r2 = 1 + 1
Reorder the terms:
1 + 2r + r2 = 1 + 1
Combine like terms: 1 + 1 = 2
1 + 2r + r2 = 2
Factor a perfect square on the left side:
(r + 1)(r + 1) = 2
Calculate the square root of the right side: 1.414213562
Break this problem into two subproblems by setting
(r + 1) equal to 1.414213562 and -1.414213562.
Subproblem 1
r + 1 = 1.414213562
Simplifying
r + 1 = 1.414213562
Reorder the terms:
1 + r = 1.414213562
Solving
1 + r = 1.414213562
Solving for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Add '-1' to each side of the equation.
1 + -1 + r = 1.414213562 + -1
Combine like terms: 1 + -1 = 0
0 + r = 1.414213562 + -1
r = 1.414213562 + -1
Combine like terms: 1.414213562 + -1 = 0.414213562
r = 0.414213562
Simplifying
r = 0.414213562
Subproblem 2
r + 1 = -1.414213562
Simplifying
r + 1 = -1.414213562
Reorder the terms:
1 + r = -1.414213562
Solving
1 + r = -1.414213562
Solving for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Add '-1' to each side of the equation.
1 + -1 + r = -1.414213562 + -1
Combine like terms: 1 + -1 = 0
0 + r = -1.414213562 + -1
r = -1.414213562 + -1
Combine like terms: -1.414213562 + -1 = -2.414213562
r = -2.414213562
Simplifying
r = -2.414213562
Solution
The solution to the problem is based on the solutions
from the subproblems.
r = {0.414213562, -2.414213562}