Solve for $x$, where $x > 0$ and $0 = -21x^2 - 11x + 40.$ Express your answer as a simplified common fraction.

Step-by-step explanation:

Hello, please consider the following.

The solutions are, for a positive discriminant:

Here, we have a = -21, b = -11, c = 40, so it gives:

So, we have two solutions:

We only want x > 0 so the solution is

Hope this helps.

Do not hesitate if you need further explanation.

Thank you

mk./km: lm

step-by-step explanation:

,mlmlm

; mk

lk

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."