All Junior Cert Mathematics posts
• #### Using the quadratic formula Zozosmithy

Hi guys, Just wondering for the quadratic formula do we make the roots a minus or plus??? For example: When using brackets for -4squared, that equals to 16. Without using brackets for -4squared, that equals to -16. In simpler terms, (-4)squared=16 and -4squared=-16. Thanks.

1. #### studyclix

Hi Zozosmithy,

If b = -4 then the b squared part would be (-4) squared which would be 16. Hope this helps.

2. #### Zozosmithy

Ok and what if b= +4?? Thanks.

3. #### studyclix

if b=4 then b squared would be +16 also.

Any number squared will be a positive i.e. 3 squared = 9, (-3) squared = 9

4. #### hamzamughees

if you have -4^2 (^ means to the power of) without brackets, the minus will not be squared, only the 4 will be squared and the minus sign will be added on to it later, e.g -4^2, the minus will be taken out, so 4^2 = 16, and then the minus will be added on, so -16. if you use the brackets, so (-4)^2, the minus will also be squared, - * - = + (* means multiply) 4 * 4 = 16, so the answer of (-4)^2 = +16, -4^2 = -16.

hope this helped:)

5. #### Dazzla16

Hi Zozosmithy! As you know this is the quadratic formula:

x=

-b +/- sqrt(b^2 - 4ac)

________________

2a

when an equation is in the form: ax^2 + bx + c

You will notice the coefficient of b^2 is positive. That means, no matter what integer you sub in for b, b^2 will be positive.

Example: If b = -3, then b^2 = (-3)^2 = 9.

In that case, you always have to put in the brackets.

6. #### Dazzla16

Hi Zozosmithy! As you know this is the quadratic formula:

x=

-b +/- sqrt(b^2 - 4ac)

________________

2a

when an equation is in the form: ax^2 + bx + c = 0

You will notice the coefficient of b^2 is positive. That means, no matter what integer you sub in for b, b^2 will be positive.

Example: If b = -3, then b^2 = (-3)^2 = 9.

In that case, you always have to put in the brackets.