1) Let w = width of the driveway.
Since the length of the driveway is 16 feet longer than the width, it follows that w + 16 is the width.
The formula for the area of the driveway is given by
A = (length) x (width), which we know the values of
A = (w + 16) w
A = w^2 + 16w
It is also given that the driveway has an area of 260 square feet. That means A = 260, and we can plug this value in for A.
260 = w^2 + 16w
Now, let's move 260 over to the right hand side, giving us
0 = w^2 + 16w - 260
At this point, we factor this.
0 = (w + 26) (w - 10)
Giving us two solutions: w = -26, w = 10
However, since the width of a driveway can never be negative, we reject w = -26, and keep w = 10.
Now that we know the width, we can obtain the length; after all, it was given to be 16 feet longer than the width. Therefore, the length is 10 + 16 = 26.
So the dimensions of the driveway are 10 feet by 26 feet.
2006-12-24 07:11:05
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answer #1
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answered by Puggy 7
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A construction company is planning to pour concrete for a driveway. The length of the driveway is 16 ft longer than its width 'w'.
Find the dimensions of the driveway if it has an area of 260 sq ft.
260ft^2=w(w+16)-w^2+16w
w^2+16w-260=0
(w+26)(w-10)=0
w>0
w=10ft
l=26ft
Janeel has a 10 inch by 12 inch photograph. She wants to scan the photograph, then reduce the result by the same amount in each dimension to post on her web site. Janeel wants the area of the image to be one eighth that of the original photograph.
1.Write an equation to represent the area of the reduced image.
2.Find the dimensions of the reduced image.
10*12=120 in^2
120/8=15in^2
(10-x)(12-x)=15
120-22x+x^2=15
x^2-22x+105=0
(x-7)(x-15)=0
x=7, 15
10-x>0
only 7 is physically possible
10-7=3
12-7=5
new dimensions are 3"5"
2006-12-24 16:51:15
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answer #2
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answered by mu_do_in 3
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OK, for the first, you just need to write an equation.
area = width times length
Then fill in the numbers you know:
260 = w * l
What else do you know?
l = w + 16
so now you have
260 = w * (w+16) = w^2 + 16w
or, w^2 + 16w - 260 = 0
Now you just need to find the roots, using the quadratic equation, or make guesses at factors of 260, which is what I just did. 260=26*10, and the difference between 26 and 10 is 16!
So, try (w-10)*(w+16) = 0
and that works!
So the possible solutions are w=10 and w=-16. But -16 doesn't make any sense for a width of something, so it must be 10!
For the second, again you just have to read carefully, write sentences, and then fill in the numbers.
The area is 1/8 of the original means
A = original/8
well, original = 10x12
so A = 10x12/8 is an equation that represents the area of the reduced image.
For the dimensions, you simply take the square root of 8 times the length of each dimension!
2006-12-24 14:47:14
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answer #3
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answered by firefly 6
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I can help with the first one:
1)w=the width
w+16=the length
260=the area
260=w(w+16)
w^2+16w=260
w^2+16w-260=0
(w+26)(w-10)=0
w=10 or -26
We throw out the -26 and use 10.
10+16=26
The dimensions are 10 ft. by 26 ft.
2006-12-24 18:22:29
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answer #4
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answered by Anonymous
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w = width
le length =w=16
a= l*w = w(w+16) = w^2+16w
so w^2+16 w = 260
w^2 +16w -260 =0
(w+26)(w-10) = 0
w - 10 = 0
w=10
so l = w+16 = 16+10 = 26
w/l = 10/12 = 5/6
wl = 120(1/8)= 15
so l =15/w
Substitute this in 1st equation to get:
w/(15/w)= 5/6
w^2/15 = 5/6
w^2= 15(5/6) =75/6 = 25/2
w = (w = approximately 5/1,414= 3.53 in
l= 15/w =15/3.53= 4.25 in
2006-12-24 15:27:20
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answer #5
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answered by ironduke8159 7
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problem 1
A = LW
260 = (w + 16)(w)
260 = w² + 16w
260 - 260 = w² + 16w - 260
0 = w² + 16w - 260
0 = (w + 26) (w - 10)
- - - - - - - -
Roots
w = - 26. . < = .Not used
w = 10
- - - - - - - -
The width is 10 feet
The length is w + 16 or 10 + 16 = 26
The length is 26 feet
- - - - - - - - - - - - - -
Check
Area = LW
260 = 26 x 10
260 = 260
- - - - - - - -s-
2006-12-24 15:15:23
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answer #6
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answered by SAMUEL D 7
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The first one, the dimensions are 26 by 10.
2006-12-25 23:04:29
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answer #7
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answered by etihad 3
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1)
(w+16).w=260
w^2+16w-260=0
width=w=12
length=w+16=12+16=28
2)
equation=ratio*width*length
=1/8 * 12*10
12*1/8=3/4
length=12-3/4=45/4
10*1/8= 5/4
10-5/4=35/4
2006-12-24 14:57:23
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answer #8
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answered by iyiogrenci 6
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