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Lilit [14]
4 years ago
9

Item 20 A bathtub is draining at a constant rate. After 2 minutes, it holds 30 gallons of water. Three minutes later, it holds 1

2 gallons of water. Write an equation that represents the number y of gallons of water in the tub after x minutes
Mathematics
1 answer:
levacccp [35]4 years ago
7 0
Y=mx+c since its at constant rate
at (30,2)
30=m2+c-----(1)
at(12,3)
12=m3+c-----(2)
by multiplying (2)by 2.5,
30=7.5m+2.5c-----(3)
by comparing (1) and (3)
2m+c=7.5m+2.5c
5.5m+1.5c=0
5.5m=-1.5c
m=-1.5/5.5c----(4)
sub 4 into 1,
-6/11c+c=30
c=66
m=-1.5/5.5*66=-18
Equation : y=-18x+66

u can try substituting back 2min and 3 mins to verify it works
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Find the distance between these points: (-3, 8) and (-5,1)
irina1246 [14]

Answer:

7.28011

Step-by-step explanation:

X1 =-3

X2 =-5

Y1 =8

Y2 =1

Distance Formula = √(X2-X1)²+ (Y2-y1)²

Step 1. calculate (X2-X1)²

(-5 - -3)2 = 4

Step 2. calculate (Y2-Y1)²

(1 - 8)2 = 49

Step 3. calculate √4 + 49

                = 7.28011

5 0
3 years ago
Constructing a brick staircase: A brick staircase has a total of 30 steps. The bottom step requires 100 bricks. Each successive
galben [10]
A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.

b) The total staircase will need: 100 + 98 + 96 + ... +  44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
7 0
3 years ago
Find ​(a) the slope of the curve at the given point​ p, and ​(b) an equation of the tangent line at p. y=−2−9x2​; ​p(2​,−38​)
Neporo4naja [7]

Answer:

a) -36

b) y = -36x +34

Step-by-step explanation:

a) The slope is found using the derivative of the function.

  f'(x) = dy/dx = 0 -9(2x) = -18x

Then at x=2, the slope is ...

  f'(2) = -18·2 = -36

___

b) The point-slope form of the equation can be written as ...

  y = -36(x -2) -38

Simplifying to slope-intercept form, we get ...

  y = -36x +34

6 0
3 years ago
Someone please help!! :^(
sineoko [7]

Answer:

equation of the table is y=30x+60

60 degrees is what the temperature starts at

to get to 440 degrees he needs 12 minutes and 40 seconds

Step-by-step explanation:

the change in y over change in x is 90/3 which is the slope

slope is 30

if slope is 30 then 30*2+b=120 60+b=120 so b=60 and it is the y intercept

440=30x+60

380=30x

x=12 2/3

x= 12 minutes and 40 seconds

8 0
4 years ago
What is the approximate area of the pizza
Dovator [93]
If you have several different sized pizzas, you can compare their areas. So the area of a pizza is the length of the crust (circumference) divided by two times the distance from the edge to the middle (radius). Mathematicians use a special number called pi to calculate the circumference of a circle.
5 0
4 years ago
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