1. ## quick algebric question...important!

Hi everyone..I have a question which was troubling me somwhow..
when I try to sketch the functions on a graph, I keep on getting lines which don't cut each other..
this is the question:

On a graph, plot the line y = 80 + 10x and y = 34x – x2. Mark clearly the y-intercept, x-intercepts, x-axis and y-axis.
Find the values of x where the two curves intersect.

2. Originally Posted by KAS
Hi everyone..I have a question which was troubling me somwhow..
when I try to sketch the functions on a graph, I keep on getting lines which don't cut each other..
this is the question:

On a graph, plot the line y = 80 + 10x and y = 34x – x2. Mark clearly the y-intercept, x-intercepts, x-axis and y-axis.
Find the values of x where the two curves intersect.

For the second equation, do you mean $\displaystyle y=34-x^2$? If so, the two functions are graphed like this:

If not, then you probably mean $\displaystyle y=34-2x$. The graph of the two lines is this:

Can you take it from here and complete the problem?

3. aha thanx a lot
I'll try ask my tutor if the function he gave was wrong or not..
n then will c ..
but if it was the first graph, does that mean that the intersection will be equal to zero?

4. if you write out a table of values for $\displaystyle y=34x-x^2$ then plot you should find a solution graphically.

x -3, -2, -1, 0, 1, 2, 3,
y -111, -72, -35, 0, 33, 64, 93

since

$\displaystyle 80 + 10x = 34x - x^2$

$\displaystyle x^2 - 24x + 80 = 0$

$\displaystyle (x-4)(x-20) = 0$

x = 4 and 20 (x,y) = (4,120) and (20,280)

5. Originally Posted by Chris L T521
For the second equation, do you mean $\displaystyle y=34-x^2$? If so, the two functions are graphed like this:

If not, then you probably mean $\displaystyle y=34-2x$. The graph of the two lines is this:

Can you take it from here and complete the problem?
Dear chris hi,

The equations which you wrote them are not correct ... they are :
$\displaystyle y=34x-2x$
or
$\displaystyle y=34x-x^2$ ..

bye