From 10574d8ee4172bdcafbc09f7bc1b59a6d49b73da Mon Sep 17 00:00:00 2001 From: James Su Date: Mon, 30 Dec 2019 03:00:19 +0000 Subject: [PATCH] Update Quadratic Functions.md --- .../Quadratic Functions.md | 65 ++++++++++++++++++- 1 file changed, 64 insertions(+), 1 deletion(-) diff --git a/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Quadratic Functions.md b/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Quadratic Functions.md index 02b9f78..b702255 100644 --- a/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Quadratic Functions.md +++ b/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Quadratic Functions.md @@ -2,4 +2,67 @@ ### Question 1 a) -As $`a`$ varies, the graph stretches when $`a \gt 1 `$ and compresses when $`0 \lt a \lt 1`$ \ No newline at end of file +As $`a`$ varies, the graph stretches when $`a \gt 1 `$ and compresses when $`0 \lt a \lt 1`$ + +As $`p`$ varies, the graph moves to either the right (when $`p`$ is negative) or left (when $`p`$ is positive). + +As $`q`$ varies, the graph moves either up (when $`q`$ is positive) or down (when $`q`$ is negative). + +### Question 1 b) + +I would first find the vertex which is equal to is at (AOS, optimal value), or $`(\dfrac{-b}{2a}, \dfrac{-b^2}{4a} + c)`$. + +In this case it would be at $`(\dfrac{-13}{6}, \dfrac{-169}{12} + 4)`$ + +Then by using the step property, which is $`1a, 3a, 5a \cdots \implies 3, 9, 15 \cdots`$, I can plot the points on the graph. In addition, since $`a`$ is positive, the graph +will be opening upward. + +### Question 2 a) + +By plugging $`3`$ as the time into the relation $`h = -5t^2 + 100t`$, we get: + +$`h = -5(3)^2 + 100(3) \implies h = -5(9) + 300 \implies h = 255`$ + +The flare will be $`255m`$ tall. + +### Question 2 b) + +The maximum height reached by the flare is when $`t = \dfrac{-b}{2a}`$ (optimal value). + +So, $`\dfrac{-b}{2a} = \dfrac{-100}{-10} = 10`$ + +$`\therefore h = -5(10)^2 + 100(10) \implies h = 500`$ + +The maximum height reached by the flare is $`500m`$. + +### Question 2 c) + +By setting $`h=80`$, we can get the 2 times where the flare reaches $`80m`$, and by taking the difference in $`x`$ values, we get the time the flare stayed above $`80m`$. + +$`80 = -5t^2 + 100t`$ + +$`5t^2 - 100t + 80 = 0`$ + +$`t^2 - 20t + 16 = 0`$ + +$`t = \dfrac{20 \pm \sqrt{366}}{2}`$ + +$`\therefore`$ The duration is $`2(\dfrac{\sqrt{336}}{2}) = \sqrt{336}`$ + +### Question 3 a) + +We can represent the area as $`hw`$, where $`h+w = 20`$, so we can model a quadratic equation as such: $`w(20-w)`$. Therefore the AOS is when $`w=10`$ + +### Question 3 b) + +Since the maximum area is when $`w = 10`$, and $`h = 20 - w \implies h = 10`$. So the dimension is a pen $`10m`$ by $`10m`$. + +### Question 4 + +The cross-sectional area can be modeled by the equation $`(50-2x)x`$. + +Therefore the AOS is when $`\dfrac{25}{2}`$ since $`x=0, 25`$ are the solutions to this quadratic equation when it equals $`0`$, and the AOS is the average of them both. + +Therefore the value of $`x=12.5cm`$ gives the maximum area for the sectional area. + +