Step-by-step explanation:
f加班7u后7个6 个预告v78 yi不同承认TVB员工
<h3>
Answer:</h3>
(a) $0.80
(b) 1.25 m
<h3>
Step-by-step explanation:</h3>
(a) Put 1 where L is, and evaluate the equation.
... p = 0.8·1 = 0.8
The cost for 1 meter of rope is $0.80.
(b) Put 1 where p is and solve for L.
... 1 = 0.8L
... 1/0.8 = L = 1.25
The length of rope that costs $1 is 1.25 meters.
bearing in mind that perpendicular lines have negative reciprocal slopes, hmmm what's the slope of the equation above?
![\bf 2x-4y+8=0\implies -4y=-2x-8\implies y = \cfrac{-2x-8}{-4} \\\\\\ y = \cfrac{-2x}{4}-\cfrac{8}{-4}\implies y = \stackrel{\stackrel{m}{\downarrow }}{-\cfrac{1}{2}}x+2\qquad \impliedby \begin{array}{|c|ll} \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array} \\\\[-0.35em] ~\dotfill](https://tex.z-dn.net/?f=%5Cbf%202x-4y%2B8%3D0%5Cimplies%20-4y%3D-2x-8%5Cimplies%20y%20%3D%20%5Ccfrac%7B-2x-8%7D%7B-4%7D%20%5C%5C%5C%5C%5C%5C%20y%20%3D%20%5Ccfrac%7B-2x%7D%7B4%7D-%5Ccfrac%7B8%7D%7B-4%7D%5Cimplies%20y%20%3D%20%5Cstackrel%7B%5Cstackrel%7Bm%7D%7B%5Cdownarrow%20%7D%7D%7B-%5Ccfrac%7B1%7D%7B2%7D%7Dx%2B2%5Cqquad%20%5Cimpliedby%20%5Cbegin%7Barray%7D%7B%7Cc%7Cll%7D%20%5Ccline%7B1-1%7D%20slope-intercept~form%5C%5C%20%5Ccline%7B1-1%7D%20%5C%5C%20y%3D%5Cunderset%7By-intercept%7D%7B%5Cstackrel%7Bslope%5Cqquad%20%7D%7B%5Cstackrel%7B%5Cdownarrow%20%7D%7Bm%7Dx%2B%5Cunderset%7B%5Cuparrow%20%7D%7Bb%7D%7D%7D%20%5C%5C%5C%5C%20%5Ccline%7B1-1%7D%20%5Cend%7Barray%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill)

so we're really looking for the equation of a line whose slope is 2 and runs through (2,-5),

<span>The answer is: [C]: " {56, 66, 71, 78, 57, 53, 69, 68, 70, 60, 59, 55} " .
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