Answer:
C.
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
Algebra I
Algebra II
Step-by-step explanation:
Step 1: Define
x² - 5x + 7 = 0
Step 2: Identify Variables
a = 1
b = -5
c = 7
Step 3: Find solutions
The solutions to the equation x² - 5x + 7 = 0 are:
x = (5 + i√3) / 2 or x = (5 - i√3) / 2
Option C is the correct answer.
We have,
To find the solutions of the quadraticequation x² - 5x + 7 = 0, we can use the quadraticformula:
x = (-b ± √(b² - 4ac)) / (2a)
For the given equation, the coefficients are:
a = 1
b = -5
c = 7
Substituting these values into the quadraticformula,
x = (-(-5) ± √((-5)² - 4(1)(7))) / (2(1))
Simplifying further:
x = (5 ± √(25 - 28)) / 2
x = (5 ± √(-3)) / 2
Since the discriminant (the value inside the square root) is negative, √(-3) is imaginary, meaning there are norealsolutions to this quadratic equation.
The solutions exist in the complex number system.
So,
√-1 = i
x = (5 ± i√3) / 2
This can be written as,
x = (5 + i√3) / 2
and
x = (5 - i√3) / 2
Thus,
The solutions to the equation x² - 5x + 7 = 0 are:
x = (5 + i√3) / 2 or x = (5 - i√3) / 2
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Question:
A boy makes a cone of diameter 28 cm without a base. He then cuts a smaller cone of diameter 20 cm from the cone. He used the bottom part as a lampshade. If the height of the lampshade is 11cm,
(a) find the volume of the whole cone.
(b) find in cm2, the area of the material used to make the lampshade.
Answer:
(a) V ≈ 16420.1
(b) A ≈ 2690.1 cm²
Step-by-step explanation:
Solution for (a)
Formula: The formula for the volume of a cone is V = 1/3 hπr².
V= πr² h/3 = π × 28/ 2 × 20/ 3 ≈ 16420.0576
16420.0576 in nearest tenths is 16420.1
Therefore, the volume of the whole cone is 16420.1 cm²
Solution for (b)
Formula: A = πrl + πr2.
l = r² + h²
Solving for A
A = πr (r + h²+ r²) = π × 20 × (20 + 112 + 202) ≈ 2690.80077
2690.80077 In nearest tenths, is 2690.1
Therefore, the area of the material used to make the lampshade is 2690.1 cm²