Question

a quality y is initially -68 and decreases at a rate of 18 per day.
find an equation y=mx+b that models the quality y after x units of time.
what is the equation that models the given situation?

Answer 1

What's your opinion for this question ?

Answer 2

its a equation

Answer 3

Show your working

Answer 4

-68x18

Answer 5

im lost

Answer 6

so we know that y=mx+b so think about how your start point is -68 that tells you that your initial y is -68 so which part of y=mx+b tell you your initial y value

Answer 7

18

Answer 8

which part of y=mx+b changes the y value is it the m or the b since you know the arent function is y=x

Answer 9

parent*

Answer 10

b

Answer 11

ok so since b changes the y value and the problem told you your initial y is -68 where should -68 go in
y=mx+b
just retype y=mx+b with where you think -68 should go

Answer 12

y=mx-68

Answer 13

ok good. Now we have to find m which we say tells us the slope of the graph. What does slope mean to you

Answer 14

y=18x-68

Answer 15

m=18, b=-68 where m is the slopeGlossary
slope
The steepness of a line expressed as a ratio, using any two points on the line. and b is the y-interceptGlossary
y-intercept
The value of y at the point where a curve crosses the y-axis.

Answer 16

yes that is correct but the idea is that the problem gives you a number and tells you it changes at a constant rate. Since it changes at a constant rate it means that it is a linear graph that is how you identify the graph type. Then you take the initial amount given and replace the b since we know linear equations are y=mx+b. After that you know your slope is that change so you take that constant rate and get m so you complete y=mx+b

Answer 17

yeah you got it that's good