Rate of Change of y= -1/72*(x-60)^2 + 90 w.r.t x when x = 0

[velocity06]

Hi everyone,

I have solved the following two questions but would like if someone can confirm whether the answers are right or wrong. The questions are:

y= -1/72*(x-60)^2+90

a. Find when the rate of change of y with respect to x is zero. (The answer i got is x=60 and y=90)

b. Find dy/dx when x=80 (The answer i got is -5/9)

Thank you

 

[velocity06]

Hi,

Could someone confirm whether my answers are right. I would really appreciate it.

So the question is:

y= -1/72*(x-60)^2 + 90

Find when the rate of change of y with respect to x is zero (My answer was x=60 and y=90)

Find dy/dx when x=80 (My answer was -5/9)

Find the coordinate of the point on the curve where dy/dx = -0.5 (My answer was (78,85.5)

Thank you

 

[Deleted member 4993]

Hi everyone,

I have solved the following two questions but would like if someone can confirm whether the answers are right or wrong. The questions are:

y= -1/72*(x-60)^2+90

a. Find when the rate of change of y with respect to x is zero. (The answer i got is x=60 and y=90) ..... How ... please share work.

b. Find dy/dx when x=80 (The answer i got is -5/9)

Thank you

.

 

[Deleted member 4993]

Hi,

Could someone confirm whether my answers are right. I would really appreciate it.

So the question is:

y= -1/72*(x-60)^2 + 90

Find when the rate of change of y with respect to x is zero (My answer was x=60 and y=90) .......... How? .......... Please share work

Find dy/dx when x=80 (My answer was -5/9) .......................................................................... How? .......... Please share work

Find the coordinate of the point on the curve where dy/dx = -0.5 (My answer was (78,85.5) .......... How? .......... Please share work

Thank you

.

 

[Harry_the_cat]

Hi everyone,

I have solved the following two questions but would like if someone can confirm whether the answers are right or wrong. The questions are:

y= -1/72*(x-60)^2+90

a. Find when the rate of change of y with respect to x is zero. (The answer i got is x=60 and y=90)

b. Find dy/dx when x=80 (The answer i got is -5/9)

Thank you

Your answers are correct, but we have no way of checking whether your method is correct.

 

[stapel]

So the question is:

y= -1/72*(x-60)^2 + 90

As posted, the equation could be interpreted in any of the following ways:

. . . . .\(\displaystyle \mbox{a. }\, y\, =\, -\dfrac{1}{72}\, (x\, -\, 60)^2\, +\, 90\)

. . . . .\(\displaystyle \mbox{b. }\, y\, =\, -\dfrac{1}{72\, (x\, -\, 60)^2}\, +\, 90\)

. . . . .\(\displaystyle \mbox{c. }\, y\, =\, -\dfrac{1}{72\, (x\, -\, 60)^2\, +\, 90}\)

Which did you intend?

Thank you!