A) 4a - 3b + 2c
4(2, -1, 5) - 3(4, 3 , -2) + 2(5, 4, 0) = (8, -4, 20) - (12, 9, - 6) + (10, 8, 0) =
= (8 - 12 + 10 , -4 - 9 + 8 , 20 + 6 + 0) = (6, - 5, 26)
Answer: (6, - 5, 26)
b) magnitude of vector b

c) vector of length 7 parallel to vector c
=> m(5,4,0) = (5m,4m,0)
=>

=> m = 7 / √41 ≈ 1.093
=> 1.093 (5, 4, 0) = (5.465 , 4.372, 0)
Answer: (5.465 , 4.372 , 0)
Answer:
EF = 58/7
Step-by-step explanation:
If you extend both BC and AD to meet at P you get 3 similar triangles PAB, PEF, and PCD. Let's call BF = 3x and FC = 4x. Therefore the following proportions can be expressed:
BP/7 = (BP+7x)/10
10BP = 7*(BP+7x)
10BP = 7BP+49x
3BP = 49x
BP = (49/3)x
BP/7 = (BP+3x)/EF
EF = (BP+3x)*7/BP
EF = ((49/3)x + 3x)*7/((49/3)x)
EF = ((58/3)x*7*3)/(49x)
EF = 58/7
The height of the water tank is 6.
L x W x H = V (volume)
15 x 10 x 6 = 900 cubic feet