SOLUTION: I need help!!! My problem is I must solve this equation by completing the square!!! The equation is r2-2r-35=0!!! Can you please help me!!!

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: I need help!!! My problem is I must solve this equation by completing the square!!! The equation is r2-2r-35=0!!! Can you please help me!!!      Log On


   

Question 142537: I need help!!! My problem is I must solve this equation by completing the square!!! The equation is r2-2r-35=0!!! Can you please help me!!!
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

r%5E2-2+r-35=0 Start with the given equation


r%5E2-2+r=35 Add 35 to both sides



Take half of the "r" coefficient -2 to get -1 (ie %281%2F2%29%28-2%29=-1).

Now square -1 to get 1 (ie %28-1%29%5E2=%28-1%29%28-1%29=1)




r%5E2-2r%2B1=35%2B1 Now add this value to both sides


r%5E2-2r%2B1=36 Combine like terms




%28r-1%29%5E2=36 Now factor r%5E2-2r%2B1 to get %28r-1%29%5E2




Take the square root of both sides


or Simplify


or Add 1 to both sides for each case


or



So our answers are or




Notice if we graph we can see that the roots are or . So this verifies our answer.

graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C1x%5E2-2x-35%29