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I won't lie, this is homework! Please help if you can. PLEASE no comments like " do your own homework"
I just don't get it, I went through this 20 years ago in high school and didn't get it.
1)x sq. -3x-10=0
2) If f(x) = 3x sqr+5x-2, find a) f(-2), b) f(4),
3) Solve 3xsqr + 19x-14=0 using the quadratic formula.
4a) Calculate the value of the discriminant of x sqr.+2x+1=0
4b) By examining the sign of the discriminant in 4a, how many intercepts would the graph of y=x sqr. +2x +1 have? why?
5) Find the corresponding y values for x= -4,-3,-2,-1,0,1,2, if y=x sqr +2x-15
O.K., Hopefully all the comments not actually required for this question are out of the way!!!
I am in the real world! I do have a paying job! I do pay attention in class. It would be better if the classes weren't on-line.
Why not ask this questions? It is called "Yahoo Answers" right?
It's supposed to be for people to ask questions to KNOWLEDGEABLE people.
4 Answers
- 1 decade agoFavorite Answer
1). x² -3x-10 = 0
factors of -10 that add to -3 ----> -5 x 2 = -10, -5+2 = -3
therefore (x-5) (x+2), therefore when x = 5, and x = -2, the eqaution is true.
2) sub in -2, and 4 into the equation.
3(-2)² + 5(-2) - 2 = 0, 3(4)² + 5(4) - 2 = 66
3) quadratic formula is x = [-b +/- sq.root( b² - 4ac)]/2a
from that x = -2/3 or -7
4a) the discriminant is the expression under the square root sign in the quadratic formula, so apply it and find out what the value is.
4b)if the value is positive, then there are two intercepts, if the value is negative, there are no intercepts, if it is zero, there is only one intercept and its the turning point.
5) sub in each x value into the equation given.
IM DEFINTELY NOT DOING THAT!!
Its simple stuff...really you shouldnt be asking this sorta stuff.
- c0ckyLv 51 decade ago
The standard quadratic formula is...errr...ax^2 + bx +c = 0
What YOU have to do is - as it is clear to me you haven't yet - is to identify once and for all what these letters stand for.
(And why you would go to all this trouble over an equation which yields 'nothing')
Then you will be able to work things like 'b^2 - 4ac, and mod ac, and that quadratic formula.
Quadratics are your first taste of the non-linear world and 0o0o0o0o0hh its so0o0o0o0 addictive...
- 1 decade ago
look in the answers lol, but seriously maybe you should do your own work cause maths is a big part in life u use it everyday...
trust me you will need it for when you get out in the real world.
and get a job so pay attention in class :p
- 1 decade ago
Umm... Why don't you try a calculator? Or maybe... PAY ATTENTION IN CLASS...
Source(s): my mind
