40x+8x^2=0 can be solved for x (there are two solutions):
Divide all 3 terms by the greatest common multiple (which is 8x):
40x+8x^2=0
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8x 8x
5 + x = 0 produces the root x = - 5.
Setting 8x = 0 and solving for x produces the root x = 0.
Be certain to check these results. substitute x = -5 into 40x+8x^2=0. Is the resulting equation true or false? Next, subs. x=-5 into 40x+8x^2=0. Is the resulting equation true or false?
SRT = 20 => STR = 20.
Since STR and STU are supplementary angles, STU = 180 - STR = 180 - 20 = 160, means x = 40.
87.5 percent
Reason: 40/40-5/40 is 35/40. Divide 35/40 and you get 0.875. Multiply by a hundred and you get 87.5%
Answer:
The required drawing showing the cliff, river, and tower as well as the details in the question is attached, please find alongside the answer
The width of the river is approximately 51.55 meters
Step-by-step explanation:
The height of the observation tower = 11 meters
The angle of elevation of the cliff top and the opposite side of the river = 20°
The angle of elevation of the tower top and the opposite side of the river = 30°
Therefore, by sine rule, we have;
h/sin(20) = w/sin(60)
11/sin(10) = length, l/sin(60)
l = sin(60) ×11/sin(10) ≈ 54.86 meters
w = l × cos (20) = 54.86 meters × cos (20) ≈ 51.55 meters
The width, w, of the river is approximately 51.55 meters.