The ages of three sisters are consecutive integers. The sum of their ages is 72. Calculate their ages.
1 answer:
Answer: 1st: 23 years old, 2nd: 24 years old, 3rd: 25 years old
Step-by-step explanation:
Let the ages a, b and c
a + b + c = 72
b = a + 1 (b is consecutive to a)
c = a + 2 (c is consecutive to b)
a + a + 1 + a + 2 = 72
3a +3 = 72
3a = 72-3 = 69
a = 69/3 = 23 years old, that is the 1st child's age
b = a + 1 = 24 years old, that is the 2nd child's age
c = a + 2 = 25 years old, that is the 3rd child's age
<h3>Verification</h3>a + b + c= 23 + 24 + 25 = 72 years
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f(x) is a parabola. It's lowest point occurs when x = 0. It is the point (0,7). At x = -4 and x=8 it has the values 11.8 and 26.2 respectively. That is, it contains the points (-4, 11.8) and (8,26.2).
From these we make a rough sketch (see attachment). This is a sketch and mine is very incorrect when it comes to scale but what matters here is which of the curves is on top, which is below and whether they intersect anywhere in the interval, so my rough sketch is good enough. From the sketch we see that f(x) is always above (greater than) g(x).
To find the area between the curves over the given interval we integrate their difference and since f(x) is strictly greater than g(x) we subtract as follows: f(x) - g(x). The limits of integration are the values -4 and 8 (the x-values between which we are looking for the area.
Now let's integrate:
The integral yields:^{3} }{3} +7(8)- \frac{ (8)^{2} }{2}) -(\frac{.3 (-4)^{3} }{3} +7(-4)- \frac{ (-4)^{2} }{2}) = 117.6](https://tex.z-dn.net/?f=%20%5Btex%5D%28%5Cfrac%7B.3%20%288%29%5E%7B3%7D%20%7D%7B3%7D%20%2B7%288%29-%20%5Cfrac%7B%20%288%29%5E%7B2%7D%20%7D%7B2%7D%29%20-%28%5Cfrac%7B.3%20%28-4%29%5E%7B3%7D%20%7D%7B3%7D%20%2B7%28-4%29-%20%5Cfrac%7B%20%28-4%29%5E%7B2%7D%20%7D%7B2%7D%29%20%3D%20117.6)
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We evaluate this for 8 and for -4 subtracting the second FROM the first to get:
f(x) is a parabola. It's lowest point occurs when x = 0. It is the point (0,7). At x = -4 and x=8 it has the values 11.8 and 26.2 respectively. That is, it contains the points (-4, 11.8) and (8,26.2).
From these we make a rough sketch (see attachment). This is a sketch and mine is very incorrect when it comes to scale but what matters here is which of the curves is on top, which is below and whether they intersect anywhere in the interval, so my rough sketch is good enough. From the sketch we see that f(x) is always above (greater than) g(x).
To find the area between the curves over the given interval we integrate their difference and since f(x) is strictly greater than g(x) we subtract as follows: f(x) - g(x). The limits of integration are the values -4 and 8 (the x-values between which we are looking for the area.
Now let's integrate:
The integral yields:
We evaluate this for 8 and for -4 subtracting the second FROM the first to get:
Answer:
-2/-3 = 2/3 this is true
Step-by-step explanatio
3/2 = 1,5 but -2/-3 = 2/3 about 0.66666...
