30 POINTS IF U ANSWER!
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The price of 1 drink is $ 4 and price of 1 pretzel is $ 4.25
<em><u>Solution:</u></em>
Let d" be the price of 1 drink
Let "p" be the price of 1 pretzel
Given that, Isabella went into a movie theater and bought 3 drinks and 10 pretzels, costing a total of $54.50
<em><u>Therefore, we can frame a equation as,</u></em>
3 x price of 1 drink + 10 x price of 1 pretzel = 54.50
3d + 10p = 54.5 ---------- eqn 1
Jason went into the same movie theater and bought 9 drinks and 5 pretzels, costing a total of $57.25
9 x price of 1 drink + 5 x price of 1 pretzel = 57.25
9d + 5p = 57.25 ---------- eqn 2
<em><u>Let us solve eqn 1 and eqn 2</u></em>
Multiply eqn 1 by 3
9d + 30p = 163.5 ----- eqn 3
<em><u>Subtract eqn 2 from eqn 3</u></em>
9d + 30p = 163.5
9d + 5p = 57.25
( - ) -----------------------
25p = 106.25
p = 4.25
<em><u>Substitute p = 4.25 in eqn 1</u></em>
3d + 10(4.25) = 54.5
3d + 42.5 = 54.5
3d = 54.5 - 42.5
3d = 12
d = 4
Thus price of 1 drink is $ 4 and price of 1 pretzel is $ 4.25
f(x) is the same as y, so we can say y = f(x)
Writing f(x) < 0 means we want to find when y < 0.
Visually, we are looking at the graph when the curve is below the horizontal x axis.
This is the portion in red that I have marked in the diagram (see attached image below). I apologize for the numbers being blurry.
The left red portion is from negative infinity to -3. In terms of a compound inequality we write which in interval notation is
. The curved parenthesis tells the reader to exclude both endpoints.
The right red portion is from x = -1.1 to x = 0.9, excluding both endpoints. So we say which becomes the interval notation
. This is not ordered pair notation even though it looks identical to it.
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<h3>Answer in interval notation:The "U" means "set union" which glues together the two separate intervals. Basically it's saying "x is either in the interval (-infinity, -3) or it is in the interval (-1.1, 0.9)"
