Here i how I would do it:<span>f(x)=−<span>x2</span>+8x+15</span>
set f(x) = 0 to find the points at which the graph crosses the x-axis. So<span>−<span>x2</span>+8x+15=0</span>
multiply through by -1<span><span>x2</span>−8x−15=0</span>
<span>(x−4<span>)2</span>−31=0</span>
<span>x=4±<span>31<span>−−</span>√</span></span>
So these are the points at which the graph crosses the x-axis. To find the point where it crosses the y-axis, set x=0 in your original equation to get 15. Now because of the negative on the x^2, your graph will be an upside down parabola, going through<span>(0,15),(4−<span>31<span>−−</span>√</span>,0)and(4+<span>31<span>−−</span>√</span>,0)</span>
To find the coordinates of the maximum (it is maximum) of the graph, you take a look at the completed square method above. Since we multiplied through by -1, we need to multiply through by it again to get:<span>f(x)=31−(x−4<span>)2</span></span><span>
Now this is maximal when x=4, because x=4 causes -(x-4)^2 to vanish. So the coordinates of the maximum are (4,y). To find the y, simply substitute x=4 into the equation f(x) to give y = 31. So it agrees with the mighty Satellite: (4,31) is the vertex.</span>
Answer:
The length of the rectangle 'l' = 20
The width of the rectangle 'w' = 14
Step-by-step explanation:
<u>Explanation</u>:-
Let 'x' be the width
Given data the length of a rectangular patio is 8 feet less than twice its width
2x-8 = length
The area of rectangle = length X width
Given area of rectangle = 280 square feet
x(2x-8) = 280
2(x)(x-4) =280
x(x-4) =140
x^2 -4x -140=0
x^2-14x+10x-140=0
x(x-14)+10(x-14)=0
(x+10)(x-14) =0
x = -10 and x = 14
we can choose only x =14
The width of the rectangle 14
The length of the rectangle 2x-8 = 2(14)-8 = 28 -8 =20
The length of the rectangle 'l' = 20
The width of the rectangle 'w' = 14
The equation is 76*120/3.
76*120/3
9,120/3
3,040
The car will travel 3,040 yards in 120 seconds at that speed.
Answer:
C is -2
Step-by-step explanation:
because A its 6
B its 2
C its -2
D -6
hope this helps
