Answer:
Only choices C and D are solutions
Step-by-step explanation:
6x + 3y = -15
y = -2x - 5
6x + 3y = -15
6x + 3(-2x - 5) = -15
6x - 6x - 15 = -15
0 = 0
Since 0 = 0 is a true statement, both equations of this system are the same equation and represent a single line on the coordinate plane.
We need to check each choice in just one equation.
Let's use the second equation.
y = -2x - 5
A. 
(2, 7)
7 = -2(2) - 5
7 = -4 - 5
7 = -9   False
Not a solution
B.
(5, 0)
0 = -2(5) - 5
0 = -10 - 5
0 = -15     False
Not a solution
C.
(-3, 1)
1 = -2(-3) - 5
1 = 6 - 5
1 = 1   True
Solution
D.
-13 = -2(4) - 5
-13 = -8 - 5
-13 = -13    True
Solution
Answer: Only choices C and D are solutions
 
        
             
        
        
        
Answer:
3 = x
Step-by-step explanation:
0 > 3x - 3 - 6
You want to group up the -3 and -6 first
0 > 3x - 9
Then you want to add 9 to each side to cancel out the negative 9 on one side.
0 > 3x - 9
+9        +9
9 > 3x
Now you just divide by 3 on each side

3 = x
 
        
             
        
        
        
For this case we have the following equation:
 H (t) = - 16t ^ 2 + 28t
 When the dolphin finishes a jump, then the height is equal to zero.
 We have then:
 -16t ^ 2 + 28t = 0
 We look for the roots of the polynomial:
 t1 = 0
 t2 = 1.75 s
 Therefore, the dolphin takes 1.75 seconds to make a jump.
 Answer:
 it will take for the dolphin to make one jump about:
 t = 1.75 s