# Tagged Questions

Questions on quadratic functions and equations, second degree polynomials usually in the forms $y=ax^2+bx+c$, $y=a(x-b)^2+c$ or $y=a(x+b)(x+c)$.

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### Find set of values for $k$ with two distinct roots?

Find the set of values for $k$ for which the line $y=2x-k$ meets the curve $y=x^2+kx-2$ at two distinct points. I have started my equation like this: $$x^2+kx-2=2x-k$$ but I need to put it in the ...
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### Indefinite Boolean Quadratic Programming: number of minima

The Boolean Quadratic Programming problem is defined as: $\min_{x} f(x) = x^TQx + c^Tx$ s.t. $x \in \{0,1\}^n$ It is a well-studied NP-Hard problem with many approximation algorithms proposed. I ...
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### Figuring $x$ and $y$ from two linear equations

I have a mini exam in a month to study for and I'm looking at systems of equations at the moment. I have this question to look at right now: Find $x$ and $y:$ $x-5y+4=1$ $\dfrac{x+1}{2}=y^2$ Now ...
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### How to expand a equation into a quadratic equation? [closed]

I need a explanation and steps how I can expand this equation: $$(x−p)^2+(mx+c−q)^2=r$$ into this one: $$(m^2+1)x^2+2(mc−mq−p)x+(q^2−r+p^2−2cq+c^2)=0$$ Thank you for your time.
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### Find the set of values of x for which $\frac{x+1}{2x-3}<\frac{1}{x-3}$

Here's what I've done: $\frac{x+1}{2x-3}<\frac{1}{x-3}$ $x+1<\frac{2x-3}{x-3}$ $(x+1)(x-3)<2x-3$ $x^2-2x-3<2x-3$ $x^2-4x<0$ $x(x-4)<0$ $0<x<4$ However this clearly ...
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### Solution to a simple system of quadratic equations

I am hoping to find a closed-form solution to the following system of $n$ quadratic equations: $$x_j^2 = \sum_{i=1}^n B_{ij}x_i$$ for $j\in\{1,\dots,n\}$, where $B_{ij}\geq 0$. There is a trivial ...
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### Involves finding minimum length as x varies

Ok in a question where you have been given coordinates for a and b (-3,5),(x,3x+9) respectively and AB^2 is given to be 10X^2+30x+25 for this 5 is taken out as a factor so you're left with 5(2x^2+6x+5)...
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### Am I finding this $x$-value correctly?

If the flight path of a cricket ball is given by: $$y = \frac{1}{3}x - \frac{1}{60}x^2$$ And a fielder standing originally at $(10, 0)$ catches the ball when it is $1.5$ units above the ground, to ...
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### $f(x)$ is a quadratic polynomial with leading coefficient $1$, $|f(x)| \leq 8 \: \forall \: x \in [1,9]$ find $f(x)$

$f(x)$ is a polynomial of the form ($b,c$ are real numbers) $$f(x) = x^2+bx+c$$ such that $|f(x)| \leq 8 \: \forall \: x \in [1,9]$. Find all $f(x)$ satisfying the given condition. I found ...
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### How do you solve a system of equations with e^x

How do you solve a system of equations with e^x. For example
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### $100 + [110/(1+r)] = [1/ (1+r)] + [(232 /(1+r)^2 ]$

Need to learn how to solve this: $100 + \frac{110}{1 + r} = \frac{1}{1 + r} + \frac{232}{(1 + r)^{2}}$. Checked this site got to the 3rd line and am completely lost. Can someone help me solve for r ...
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### finding rational roots

Consider the integral expression in $x$ $$P=x^3+x^2+ax+1,$$ where $a$ is a rational number. At $a= ?$ the value of $P$ is a rational number for any $x$ which satisfies the equation $x^2+2x−2=0$, and ...
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