# 26 algebra?
回答 (4)
2015-08-29 8:53 pm
✔ 最佳答案
Area of rectangle = 3x(x+2)Area of triangle = 0.5*3x^2
3x^2+6x+1.5x^2 = 336
4.5x^2+6x-336 = 0
3x^2+4x-224 = 0
(3x+28)(x-8) = 0
x = 8
Length = 24 ft
Height = 10 ft
2015-08-29 8:59 pm
A=3x(x+2)+x(3x)/2
A=3x^2+6x+3x^2/2
A=(6x^2+12x+3x^2)/2
A=(9x^2+12x)/2 and A=336
(9x^2+12x)/2=336
9x^2+12x=672
9x^2+12x-672=0
3x^2+4x-224=0
x=[-4±52]/6
x=(8, -9 1/3) since x>0, x=8
So the width is 24ft and the height if 10ft
check...
24(10)+24(8)/2=336ft^2
A=3x^2+6x+3x^2/2
A=(6x^2+12x+3x^2)/2
A=(9x^2+12x)/2 and A=336
(9x^2+12x)/2=336
9x^2+12x=672
9x^2+12x-672=0
3x^2+4x-224=0
x=[-4±52]/6
x=(8, -9 1/3) since x>0, x=8
So the width is 24ft and the height if 10ft
check...
24(10)+24(8)/2=336ft^2
2015-08-29 8:57 pm
[(1/2) * x * 3x] + [3x * (x + 2)] = 336
(3/2)x^2 + 3x^2 + 6x = 336
(9/2)x^2 + 6x - 336 = 0
(x - 8)(3x + 28) = 0
x = -28/3, 8
Since x > 0, x = 8 feet
l : x + 2 = 10 feet
w : 3x = 24 feet
(3/2)x^2 + 3x^2 + 6x = 336
(9/2)x^2 + 6x - 336 = 0
(x - 8)(3x + 28) = 0
x = -28/3, 8
Since x > 0, x = 8 feet
l : x + 2 = 10 feet
w : 3x = 24 feet
2015-08-29 8:52 pm
again ...you should know how to compute the areas of a rectangle and a triangle...and thus be able to work this problem..........{ 24 by 10 }
收錄日期: 2021-04-21 13:49:45
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https://hk.answers.yahoo.com/question/index?qid=20150829124118AAOAETv