Answer:
The correct option is option B. It has one solution, and it's x=-3
Step-by-step explanation:
We have the following system of equations:
5x+7 = 2y (1)
y-9x=23 (2)
Step 1: Solve for 'y' in equation (2):
y-9x = 23
y = 9x + 23
Step 2: Substitute in equation (1):
5x + 7 = 2y
5x + 7 = 2(9x + 23)
5x + 7 = 18x + 46
Step 3: Solve for x:
7 - 46 = 18x - 5x
-39 = 13x
x= -3
So the correct option is option B. It has one solution, and it's x=-3
Answer:
24
Step-by-step explanation:
Do i need to explain ??????
-10t - (-17t) - 10t + (-13) = 11 (two negative signs makes a positive)
-10t + 17t - 10t - 13 = 11 Combine like terms
-3t - 13 = 11 Add 13 on both sides
-3t = 24 Divide -3 on both sides
t = -8
Answer:
d. 20
Step-by-step explanation:
Standard deviation is 4.5
Margin error for the problem is 2 hours
Probability 95%, that means that the siginficance level α is 1 – p
α = 1 – 0.95 = 0.05
margin of error (ME) can be defined as follows
ME = Z(α/2) * standard deviation/ √n
Where n is the sample size
Z(0.05/2) = Z(0.025)
Using a z table Z = 1.96
Now, replacing in the equation and find n
2 = 1.96 * 4.5/ √n
2 = 8.82/√n
√n = 8.82/2
√n = 4.41
n = 4.41^2
n = 19.44 ≈ 20
The mean can be found by adding the two numbers and dividing by 2
let the second number be y
(x + y)/2 = 1/2x + 1
solve for y
multiply each side by 2
x + y = 2(1/2x + 1)
distribute
x + y = x + 2
subtract x on both sides
y = 2
ANSWER: the second number is 2
