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Solve using the quadratic formula: x2 – 3x – 3 = -5?
11 Answers
- Anonymous1 decade ago
The quadratic formula is -b+or-[b^2-4ac]/2a, and the abc are the coefficients from your equation when in this form: ax^2+bx+c. So using that information, start substituting numbers into the formula:
-(-3)+or-[(-3)^2-4(1)(2)]/2(1) and do the math
3+or-[9-8]/2
3+or-(1)/2
3+or-0.5
3+0.5=3.5 or
3-0.5=2.5
x=3.5 or x=2.5
Now you have to plug these values into the equation to see which is correct.
I didn't see your -5, so my math is wrong. You have to add 5 to both sides, making c=+2. I went back and fixed it.
wpf.
- Anonymous5 years ago
Hi , I think you the formula and you shall get the answer.Let's try to derive an formula for a general quadratic terms . Let us take a quadratic equation ax^2+bx+c = 0 Now we have to derive the value of "x". If p*q = 0 then we get EITHER p = 0 OR q = 0. So if I get in terms of p,q we get our answer.So let us try. ------> Multiply by 4a on both sides we get (2ax)^2+2(2ax)(b)+4ac = 0. ------->Now let us try to get in the formula of (a+b)^2.Addind and subtracting b^2 on the left hand side we get (2ax)^2+2(2ax)(b)+b^2--b^2+4ac = 0 --------> Now I write the first three terms as ( 2ax+b)^2 and take "--" common in the second so I get a formula of p^2--q^2 that can be written in the form of (p+q)(p--q) ---------> ( 2ax+b)^2--{sqrt(b^2--4ac)}^2 = 0 ---------> {2ax+b+sqrt(b^2--4ac)} {2ax+b--sqrt(b^2--4ac)} = 0 ----------> x = [--b+(or)--{sqrt(b^2--4ac)}]/2a NOTE:This formula is applicable whan quadratic equation is in standard form. Now let us solve your problem taking a = 1 b = --3 c = --8 (By transforming 5 on the other side) Apply the above formula x = [--(--3)+(or)--{sqrt((--3)^2--4(1)(--8)}... By solving you get x = [3+(or)--sqrt41]/2 ANSWER: x = [3+(or)--sqrt41]/2
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- 1 decade ago
r u n lyke 7 or 8 th grade
pre algebra
add +3 to -3 and -5
3x crosess out
u have x2-3x= -8
add 3x to both sides
u have x2=IDK
Source(s): http://www.getref.com/index.asp?id=LILRONELL - 1 decade ago
By quadratic formula, do you mean: x=-b [+ or -] square root of [b^2 - 4ac] all divided by [2a]?
Well then, a=1 b=-3 and c=-3
Plug it in...
But I don't know what you use the -5 for...
- 1 decade ago
Add like terms together making -1x -3 = -5. Then you get rid of what is added to the variable and coefficent on both sides of the equation so you then -1x=-5. Divide both sides of the equation by -1 and you get
x=5
- Wile E.Lv 71 decade ago
x² - 3x - 3 = - 5
x² - 3x - 3 + 5
x² - 3x + 2 = 0
(a = 1, b = - 3, c = 2)
Solution set: x{1, 2}.
See solution below: