The option C) y = 15/x
a) y = 15 x is an example of direct variation, with proportionality constant = 15
b) is an example of linear variation (it is the equation of a straight line that does not pass through the origin)
c) y = 15/x => y*x = 15 = constant which is the characteristic of an inverse relation
d) y = x/15 is an example of an inverse relation, with proportion constant = 1/15
Simplify 3x -2x -2x = 3x + -2x + -2x
Combine like terms: 3x + -2x + -2x = (3x + -2x +-2x) = -x
answer is: -x
a vertical axis, I assume it means a vertical axis of symmetry, thus it'd be a vertical parabola, like the one in the picture below.
![\bf ~~~~~~\textit{parabola vertex form} \\\\ \begin{array}{llll} y=a(x- h)^2+ k\qquad \qquad \leftarrow vertical\\\\ x=a(y- k)^2+ h \end{array} \qquad\qquad vertex~~(\stackrel{}{ h},\stackrel{}{ k}) \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \begin{cases} h=0\\ k=0 \end{cases}\implies y=a(x-0)^2+0 \\\\\\ \textit{we also know that } \begin{cases} x=-2\\ y=3 \end{cases}\implies 3=a(-2-0)^2+0\implies 3=4a \\\\\\ \cfrac{3}{4}=a~\hspace{10em}y=\cfrac{3}{4}(x-0)^2+0\implies \boxed{y=\cfrac{3}{4}x^2}](https://tex.z-dn.net/?f=%5Cbf%20~~~~~~%5Ctextit%7Bparabola%20vertex%20form%7D%20%5C%5C%5C%5C%20%5Cbegin%7Barray%7D%7Bllll%7D%20y%3Da%28x-%20h%29%5E2%2B%20k%5Cqquad%20%5Cqquad%20%5Cleftarrow%20vertical%5C%5C%5C%5C%20x%3Da%28y-%20k%29%5E2%2B%20h%20%5Cend%7Barray%7D%20%5Cqquad%5Cqquad%20vertex~~%28%5Cstackrel%7B%7D%7B%20h%7D%2C%5Cstackrel%7B%7D%7B%20k%7D%29%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20%5Cbegin%7Bcases%7D%20h%3D0%5C%5C%20k%3D0%20%5Cend%7Bcases%7D%5Cimplies%20y%3Da%28x-0%29%5E2%2B0%20%5C%5C%5C%5C%5C%5C%20%5Ctextit%7Bwe%20also%20know%20that%20%7D%20%5Cbegin%7Bcases%7D%20x%3D-2%5C%5C%20y%3D3%20%5Cend%7Bcases%7D%5Cimplies%203%3Da%28-2-0%29%5E2%2B0%5Cimplies%203%3D4a%20%5C%5C%5C%5C%5C%5C%20%5Ccfrac%7B3%7D%7B4%7D%3Da~%5Chspace%7B10em%7Dy%3D%5Ccfrac%7B3%7D%7B4%7D%28x-0%29%5E2%2B0%5Cimplies%20%5Cboxed%7By%3D%5Ccfrac%7B3%7D%7B4%7Dx%5E2%7D)
Answer:
x = 12.1
Step-by-step explanation:
20 − (z + 7) = 0.9
Distribute the minus sign
20 -x -7 = .9
Combine like terms
13 -x = .9
Subtract 13 from each side
-x = -12.1
x = 12.1
