Quadratic and linear Intersection

AI Thread Summary
The discussion revolves around finding the points of intersection between the line y = x and the parabola y = 6x - x² - 10. The user initially attempted to solve the equation but received an incorrect mark from the teacher. They used the quadratic formula's discriminant (b² - 4ac) to determine the number of intersections but faced confusion regarding their calculations. After some back and forth, the user clarified that they had mistakenly typed their answer and confirmed it was A (none). The thread highlights the importance of clear communication and accurate calculations in solving quadratic equations.
master_333
Messages
25
Reaction score
0

Homework Statement


How many points of intersection does the line y = x have with the parabola y = 6x − x2 −10 ?
A) none
B) one
C) two
D) three
E) more than three

Homework Equations

The Attempt at a Solution


x = 6x - x^2 - 10
-x^2+5x - 10
Used b^2 - 4ac to check the number of intersections.

The answer I got is . However my teacher marked it as incorrect. I still cannot find the problem, please help. If my teacher marked it wrong, please tell me so because I think he did. Thanks.
 
Physics news on Phys.org
master_333 said:

The Attempt at a Solution


x = 6x - x^2 - 10
-x^2+5x - 10
Used b^2 - 4ac to check the number of intersections.

The answer I got is . However my teacher marked it as incorrect. I still cannot find the problem, please help. If my teacher marked it wrong, please tell me so because I think he did. Thanks.

What was your answer? What did you plug in for b2 - 4ac? Your approach is correct, but I'd draw a graph to be sure. (Hint: you know the parabola is negative, and you know the y-intercept is -10.)
 
master_333 said:

Homework Statement


How many points of intersection does the line y = x have with the parabola y = 6x − x2 −10 ?
A) none
B) one
C) two
D) three
E) more than three

Homework Equations

The Attempt at a Solution


x = 6x - x^2 - 10
-x^2+5x - 10
Where did the = go? You have it two lines above, but not in the line above here.
master_333 said:
Used b^2 - 4ac to check the number of intersections.

The answer I got is .
Is what?
master_333 said:
However my teacher marked it as incorrect.
Your teacher marked what as incorrect?
You need to give us enough information so that we can provide meaningful help.
master_333 said:
I still cannot find the problem, please help. If my teacher marked it wrong, please tell me so because I think he did. Thanks.
 
Sorry I know the right answer now. However I typed it in wrong. I forgot to write that the answer i got is A . Thanks
 
master_333 said:
Sorry I know the right answer now. However I typed it in wrong. I forgot to write that the answer i got is A . Thanks
Are you saying that your teacher's answer is not A, or that you typed the question wrongly (or both)?
 

Thread 'Finding the number of ways to arrange identical balls in a circle (3 different colors)'

I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
View full post »

Thread 'Greatest possible value of a constant in polynomial'

Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
View full post »

Similar threads

Intersection of a circle and a parabola
Replies
5
Views
4K
Straight line intersects geometric sequence
Replies
5
Views
1K
Circle Geometry with an Intersecting Line
Replies
14
Views
2K
Conceptual question on equations of the form ##x=ay^2+by+c##
Replies
5
Views
2K
Quadratic function minimal value
Replies
11
Views
2K
Conditional Probability + Poisson Distribution
Replies
14
Views
3K
Where Do the Graphs of |3x-2| and 1/x Intersect and Diverge?
Replies
4
Views
2K
Possible values an expression can take : ##\dfrac{x^2-x-6}{x-3}##
Replies
7
Views
1K
Formula for Xo and Yo for graph of quadratic function
Replies
2
Views
2K
Describing an object made by the intersection of 2 surfaces
Replies
17
Views
3K

Hot Threads

Recent Insights

Back
Top