Solving Equations By Factoring

[RaulJ]

I'm having trouble with this problem ...
The problem is ...
64m^2=81
I tried to solve the problem and the answer I got was 9/8, I want to know if its right.

 

[Mrspi]

I'm having trouble with this problem ...
The problem is ...
64m^2=81
I tried to solve the problem and the answer I got was 9/8, I want to know if its right.

9/8 is correct, but there is another solution that you missed.

Here's how I would approach this problem. Subtract 81 from both sides so that you get 0 on the right-hand side of the equation:

64m<SUP>2</SUP> - 81 = 0

Factor the left side as a difference of two squares (note that 64m<SUP>2</SUP> is the square of 8m, and 81 is the square of 9:

(8m + 9)(8m - 9) = 0

Now, since the product of these two factors is equal to 0, at least one of the factors must have a value of 0. So,

8m + 9 = 0 or 8m - 9 = 0

Solve each of these equations, and you will have the two solutions of your original equation.

I hope this helps you.

 

[RaulJ]

thank you