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Swageraid32
@tcarroll010 can you help me with 4 and 5 of this....
those are my last two please........... ;/
# 4 D = b^2 - 4ac D = (1)^2 - 4(0.05)(1) D = ???
I'm sorry. I don't know any of this. I tried. I'm really really really sorry. :(((
if you have a the equation of a parabola in standard form: y= ax^2 + bx +c you match up the coefficients of your equation with a, b, and c then use those numbers for a, b, and c in the formula discriminant= b^2 -4ac jim_t already did most of the work for you.
y= 0.05 x^2 + 1x + 1 is your equation
I think phi has got you covered
you mean that is how i do the quadratic part??
we are doing question 4. They want to know the discriminant (of your quadratic equation) I assume they mean the equation they give in question 1 To find the discriminant we first do step 1: first step: pattern match y= 0.05 x^2 + 1x + 1 y= a x^2 +b x + c what is a,b, and c?
i have that part i need number 5
what did you get for a, b and c
wait what?? like for the explanation part??
D = (1)^2 - 4(0.05)(1)
I see you copied Jim's answer To find the discriminant we first do step 1: first step: pattern match y= 0.05 x^2 + 1x + 1 y= a x^2 +b x + c what is a,b, and c?
almost, b is just 1 (we only want the numbers. a= 0.05, b=1 , c=1 step 2: replace the letters a, b, and c in b^2 - 4ab with the numbers you just found (remember b^2 is short for b*b 4ab is short for 4*a*b * means multiply
now what is 1^2 ? 1*1 = 1 4*0.05 is 0.2 0.2*1 is 0.2 so 1- .2 = 0.8 the discriminant is 0.8
ok i get that thanks for actually working with me and not giving just the answer :D
so could you assist me in #5 as well??
For 5, the quadratic formula is \[ x=\frac{−b±\sqrt{b^2−4ac}}{2a}\] notice that the stuff inside the square root is the "discriminant", which you already figured out is 0.8 you also know what a, b and c are. So replace the letters with numbers what do you get?
a=0.05, b=1, c=1 \[x=\frac{−1±\sqrt{1^2- 4\times0.05\times1}}{2\times0.05}\]
@phi ?? like that??
I just noticed that the equation you have from question 1 should be y= 0.05x^2 -x +1 notice that b is -1 (not +1) this changes your answers (gack!)
yea i know it is a typo the graph is wrong
if we use b= -1 we get \[x= \frac{1 ± \sqrt{0.8}}{0.1}= 10±\sqrt{80} = 10± 4\sqrt{5} \] you get two answers x= 10+4sqrt(5) and x= 10-4sqrt(5) these are where the graph crosses the x-axis
the part like so i need to switch it to a -1?
It's your call. The question says find the equation, from the graph. Did you find the equation from the graph? If so, you got it wrong?
o wow no i used the graph that was provided on the graph ;( that means i have to go back and do this all again :/
Q1 general equation is y=0.05 x^2 -x +1 vertex form is 0.05(x-10)^2 - 4
so that means its this? y= 0.05 x^2 -1x + 1
in Q2, the -10 become +10 so that means its this? y= 0.05 x^2 -1x + 1 Yes
in Q2, the domain are all valid x's in this case, -inf to +infinity
in Q2, the range is all y values. from the graph, you see y is always bigger than -4
in Q3, your x-intercepts should be positive
in Q4, b is -1 not +1, but it won't change the discriminant calculation.
ok thanks for all that :D
i do need your help again though i mean how are you supposed to find the domain and range? @phi