Answer:
There are 120 1st graders at Sierra Elementary School this year
Step-by-step explanation:
Let n represent the total number of 1st graders at Sierra Elementary School
Since 45% of all 1st graders at Sierra Elementary School are female students and this year there are 54 female 1st graders, 45% of n is equal to 54
→ n() = 54
→ 45n = 5400
→ n = 120
Answer:
yes
Step-by-step explanation:
The line intersects each parabola in one point, so is tangent to both.
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For the first parabola, the point of intersection is ...
y^2 = 4(-y-1)
y^2 +4y +4 = 0
(y+2)^2 = 0
y = -2 . . . . . . . . one solution only
x = -(-2)-1 = 1
The point of intersection is (1, -2).
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For the second parabola, the equation is the same, but with x and y interchanged:
x^2 = 4(-x-1)
(x +2)^2 = 0
x = -2, y = 1 . . . . . one point of intersection only
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If the line is not parallel to the axis of symmetry, it is tangent if there is only one point of intersection. Here the line x+y+1=0 is tangent to both y^2=4x and x^2=4y.
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Another way to consider this is to look at the two parabolas as mirror images of each other across the line y=x. The given line is perpendicular to that line of reflection, so if it is tangent to one parabola, it is tangent to both.
We want to know how much is the price per pound (or unit rate) of ground beef, given that we know the price for Elliot's purchase. We will see that each pound costs $4.75
So we know that (3 + 2/5) lb of ground beef costs $16.15, the cost of a single pound will be given by the quotient between the total cost and the amount purchased, then we need to solve:
We can rewrite the denominator as:
(3 + 2/5)lb = (15/5 + 2/5)lb = (17/5) lb
Replacing that we get:
So each pound of ground beef costs $4.75
If you want to learn more about unit rates, you can read: