Two numbers whose sum is -1 and product is -20

Let the two numbers be x and y.

Then x + y = 20, and y = 20 - x.

Their product is what you get when you multiply the two numbers together, in other words xy, or x(20 - x). You can expand this out to get 20x - x².

The product of the two numbers will be maximum at the value

Step-by-step explanation:

sorry if this didn't help

- "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."