Online Course Discussion Forum
Math Challenge IC Handout 7
What does 7.22 mean? I'm confused. Do I pick one of the two equations on the bottom question as my expression? Do I try to calculate x,y,z according to the equations? I did that, but I don't think those values are what the question is looking for.
Thank you so much!
The problem is first showing you the same example as in 7.2. The equations you want to use are $x+y = 2$ and $y-z = 1$. Try using one of the equations to solve for $x$. Then use the other equation to write $x$ in terms of $z$ as well.
Thanks! Um... How exactly do you solve for x? I tried coming up with different variations of the parent equations and substituting... It just keeps going back to the parent equations.
In the example that is mentioned in the problem, solving for $y$ in the equation $x - y = 0$ yields, $y = x$, so you can turn the equation $x+y+z=1$ into an equation that has only $x$ and $z$: $x+x+z = 1$, so $\displaystyle x = \frac{1-z}{2}$. Since we already knew that $x=y$, we have the line is determined by the equation $\displaystyle x = y = \frac{z-1}{2}$. Note we have $$\text{something in terms of only x} = \text{something in terms of only y} = \text{something in terms of only z}.$$
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