Solve 3x(x+2)=-18: Is -1+or-the square root of 5 Correct?

Thread starter aisha
Start date Nov 30, 2004

In summary, the conversation discusses how to solve the equation 3x(x+2)=-18, with the first step being to expand the brackets. To isolate the variable x, one must combine like terms and move all other terms to the other side of the equation. It is not necessary to use the quadratic formula, as the equation can be solved using basic algebraic manipulation. The equation has two solutions, one positive and one negative, due to it being a quadratic equation. The solution -1+or-the square root of 5 is correct, but it is important to note that there is an alternative solution of -1-or-the square root of 5 as well.

Nov 30, 2004

aisha

Solve 3x(x+2)=-18 by completing square and quadratic formula. I did both methods and got -1+or-the square root of 5 i
Can someone just tell me if this is correct?

Last edited: Nov 30, 2004

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Nov 30, 2004

Gokul43201

Staff Emeritus

Science Advisor

Gold Member

Is that +18 or -18 ?

You're right if it's +18 and the RHS of the equation is " = 0 ".

Last edited: Nov 30, 2004

Nov 30, 2004

aisha

Yes sorry the equation was =-18
Thanks for checking

FAQ: Solve 3x(x+2)=-18: Is -1+or-the square root of 5 Correct?

1. What is the first step in solving the equation 3x(x+2)=-18?

The first step in solving this equation is to expand the brackets by multiplying 3x by both terms inside the brackets.

2. How can I isolate the variable x in this equation?

To isolate the variable x, you will need to combine like terms and then move all other terms to the other side of the equation using the appropriate operations.

3. Is it necessary to use the quadratic formula to solve this equation?

No, it is not necessary to use the quadratic formula to solve this equation. It can be solved by using basic algebraic manipulation and the properties of equations.

4. How many solutions does this equation have?

This equation has two solutions, one positive and one negative. This is because the equation is a quadratic equation and quadratic equations can have up to two real solutions.

5. Is the solution -1+or-the square root of 5 correct?

Yes, the solution -1+or-the square root of 5 is correct. However, it is important to note that there is an alternative solution of -1-or-the square root of 5 as well, making the two solutions -1+the square root of 5 and -1-the square root of 5.