Answer:
Option C and D are correct.
Step-by-step explanation:
Area of rectangle = 144 cm^2
Width of rectangle = 9 cm
Length of rectangle = ?
We know,
Area of rectangle = Length * Width
144 = Length * 9
144/9 = Length
=> length = 16 cm
Option A is incorrect as 3 times width = 3* 9 = 27 but our length = 16 cm
Option B is incorrect as length = 16 cm and not 63 cm
Option C is correct as Length < 2(Width) 
=> 16 < 2(9) => 16 < 18 which is true.
Option D is correct.
Perimeter = 2(Length + Width)
Perimeter = 2(16+9)
Perimeter = 50 cm
Option E is incorrect as Length ≠ Width
 
        
                    
             
        
        
        
        
Answer:
You have to upload a pic of you're work? 
Step-by-step explanation:
 
        
             
        
        
        
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)
 
        
        
        
Slope of line = tan(120) = -tan(60) = - √3
Distance from origin = 8
Let equation be Ax+By+C=0
then -A/B=-√3, or
B=A/√3.
Equation becomes
Ax+(A/√3)y+C=0
Knowing that line is 8 units from origin, apply distance formula
8=abs((Ax+(A/√3)y+C)/sqrt(A^2+(A/√3)^2))
Substitute coordinates of origin (x,y)=(0,0)  =>
8=abs(C/sqrt(A^2+A^2/3))
Let A=1 (or any other arbitrary finite value)
solve for positive solution of C
8=C/√(4/3) => C=8*2/√3 = (16/3)√3
Therefore one solution is
x+(1/√3)+(16/3)√3=0
or equivalently
√3 x + y + 16 = 0
Check:
slope = -1/√3  .....ok
distance from origin
= (√3 * 0 + 0 + 16)/(sqrt(√3)^2+1^2)
=16/2
=8  ok.
Similarly C=-16 will satisfy the given conditions.
Answer  The required equations are
√3 x + y = ± 16 
in standard form.
You can conveniently convert to point-slope form if you wish.