# Algebra

posted by Charly

I was given this answers to a problems I solved but I do not understand what she means hope you can help.

Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation. Explain your reasoning. Finally, solve the equation.
(x - 9)2 = 81

I too, came up with the same answer and agree that this is a positive number and we should expect there to be two solutions to this problem. Carrying out the square is exactly the same as using the quadratic formula it is where you substitute a, b and c into the formula. It gives you the same answer to the polynomial used. This is because the quadratic formula came from finishing the square. Completing the square method is like the father of the quadratic formula.

(x - 9)2 = 81
(x - 9) = ã81
x = 9}9
x = 18 or x = 0

This answer was inreponce to another student who came up with the same as i did.

Hi Charly,

Yes, your answer is correct. Nice work. However, the method you used is not completing the square. Which one might it be, do you think?

1. PsyDAG

For you information, online "^" indicates an exponent, e.g., x^2 = x squared.

(x - 9)^2 = 81

x^2 -18x + 81 = 81

x^2 - 18x = 0

x(x-18) = 0

X = 18 or 0

## Similar Questions

1. ### algebra

Why are there two solutions in the quadratic equation and Why do you factor a quadratic equation before you solve it
2. ### Algebra problems

I have some problems that I would like checked please. Find and simplify the difference quotient f(x+h)-f(x)/h, h can not equal 0 for the given functions. 1. f(x)=x^2+3x+9- I got 2x+h+3 Evaluate the piecewise function at the given …
3. ### algebra II

How do you know if a quadratic equation will have one, two, or no solutions?
4. ### Math

I'm using the quadratic equation and I understand how to use it, but the format my text book gives the answers in is what I don't understand. If I have (2+/-Sqrt(8))/2 I know that x can either equal 2.41 or -0.14 However, my textbook …
5. ### algebra II

How do you know if a quadratic equation will have one, two, or no solutions?
6. ### math algebra

Part 1: Which part of the quadratic formula tells you whether the quadratic equation can be solved by factoring and why?
7. ### Algebra

I was given this answers to a problems I solved but I do not understand what she means hope you can help. Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation. Explain …
8. ### Algebra II

1)What method(s) would you choose to solve the equation: x2 + 2x - 6 = 0 A. Square roots; there is no x-term. B. Quadratic formula, graphing; the equation cannot be factored easily since the numbers are large. C. Factoring; the equation …
9. ### Math

Solve the given quadratic equation exactly using the quadratic formula. Write the solutions in its simplest form. Using a calculator, determine all irrational solutions to the nearest thousandth. Separate the solutions with a comma …
10. ### Math

Solve the given quadratic equation exactly using the quadratic formula. Write the solutions in its simplest form. Using a calculator, determine all irrational solutions to the nearest thousandth. Separate the solutions with a comma …

More Similar Questions