None of your options, not via complete the square nor quadratic the formula.
Solve for x over the real numbers:
x^2 + 8 x + 9 = 0
x = (-8 ± sqrt(8^2 - 4×9))/2 = (-8 ± sqrt(64 - 36))/2 = (-8 ± sqrt(28))/2:
x = (-8 + sqrt(28))/2 or x = (-8 - sqrt(28))/2
sqrt(28) = sqrt(4×7) = sqrt(2^2×7) = 2sqrt(7):
x = (2 sqrt(7) - 8)/2 or x = (-2 sqrt(7) - 8)/2
Factor 2 from -8 + 2 sqrt(7) giving 2 (sqrt(7) - 4):
x = 1/22 (sqrt(7) - 4) or x = (-2 sqrt(7) - 8)/2
(2 (sqrt(7) - 4))/2 = sqrt(7) - 4:
x = sqrt(7) - 4 or x = (-2 sqrt(7) - 8)/2
Factor 2 from -8 - 2 sqrt(7) giving 2 (-sqrt(7) - 4):
x = sqrt(7) - 4 or x = 1/22 (-sqrt(7) - 4)
(2 (-sqrt(7) - 4))/2 = -sqrt(7) - 4:
Answer: x = sqrt(7) - 4 or x = -sqrt(7) - 4_____________________________________________________
Solve for x:
x^2 + 8 x + 9 = 0
Subtract 9 from both sides:
x^2 + 8 x = -9
Add 16 to both sides:
x^2 + 8 x + 16 = 7
Write the left hand side as a square:
(x + 4)^2 = 7
Take the square root of both sides:
x + 4 = sqrt(7) or x + 4 = -sqrt(7)
Subtract 4 from both sides:
x = sqrt(7) - 4 or x + 4 = -sqrt(7)
Subtract 4 from both sides:
Answer: x = sqrt(7) - 4 or x = -4 - sqrt(7)
Answer:
Some students were asked how many books they were carrying in their backpacks. The data is given in this frequency table. What is the mean number of pens carried by these students in their backpacks?
Pens Frequency
0 4
1 5
2 8
3 4
4 3
5 1
A.2
B.3.5
C.4
D.5.5
Answer:
P = 2000 * (1.00325)^(t*4)
(With t in years)
Step-by-step explanation:
The formula that can be used to calculated a compounded interest is:
P = Po * (1 + r/n) ^ (t*n)
Where P is the final value after t years, Po is the inicial value (Po = 2000), r is the annual interest (r = 1.3% = 0.013) and n is a value adjusted with the compound rate (in this case, it is compounded quarterly, so n = 4)
Then, we can write the equation:
P = 2000 * (1 + 0.013/4)^(t*4)
P = 2000 * (1.00325)^(t*4)
Answer:
4.5 miles
Step-by-step explanation:
2 times as far as last week
last week was 2.25 miles
2* 2.25 = 4.5 miles