$4x^2-6x+1=0\\\\a=4,\ b=-6,\ c=1\\\\\Delta=b^2-4ac\\\\\Delta=(-6)^2-4(4)(1)=36-16=20\\\\\sqrt\Delta=\sqrt{20}=\sqrt{4\cdot5}=\sqrt4\cdot\sqrt5=2\sqrt5\\\\x_1=\dfrac{-b-\sqrt\Delta}{2a},\ x_2=\dfrac{-b+\sqrt\Delta}{2a}\\\\x_1=\dfrac{-(-6)-2\sqrt5}{2\cdot4}=\dfrac{3-\sqrt5}{4}\\\\x_2=\dfrac{-(-6)+2\sqrt5}{2\cdot4}=\dfrac{3+\sqrt5}{4}$

5 0

3 years ago

A system contains n atoms, each of which can only have zero or one quanta of energy. How many ways can you arrange r quanta of e

My name is Ann [436]

Answer:

$\mathbf{a)} 2\\ \\ \mathbf{b)} 184 \; 756 \\ \\\mathbf{c)} \dfrac{(2\times 10^{23})!}{(10^{23}!)(10^{23})!}$

Step-by-step explanation:

If the system contains $n$ atoms, we can arrange $r$ quanta of energy in

$\binom{n}{r} = \dfrac{n!}{r!(n-r)!}$

ways.

$\mathbf{a)}$

In this case,

$n = 2, r=1$ .

Therefore,

$\binom{n}{r} = \binom{2}{1} = \dfrac{2!}{1!(2-1)!} = \frac{2 \cdot 1}{1 \cdot 1} = 2$

which means that we can arrange 1 quanta of energy in 2 ways.

$\mathbf{b)}$

In this case,

$n = 20, r=10$ .

Therefore,

$\binom{n}{r} = \binom{20}{10} = \dfrac{20!}{10!(20-10)!} = \frac{10! \cdot 11 \cdot 12 \cdot \ldots \cdot 20}{10!10!} = \frac{11 \cdot 12 \cdot \ldots \cdot 20}{10 \cdot 9 \cdot \ldots \cdot 1} = 184 \; 756$

which means that we can arrange 10 quanta of energy in 184 756 ways.

$\mathbf{c)}$

In this case,

$n = 2 \times 10^{23}, r = 10^{23}$ .

Therefore, we obtain that the number of ways is

$\binom{n}{r} = \binom{2\times 10^{23}}{10^{23}} = \dfrac{(2\times 10^{23})!}{(10^{23})!(2\times 10^{23} - 10^{23})!} = \dfrac{(2\times 10^{23})!}{(10^{23}!)(10^{23})!}$

3 0

2 years ago

Which expression has a value of 15 when n = 7?

sweet [91]

The answer is D.

Explanation- 28/7=4

19-4 =15

6 0

3 years ago

Can someone solve this

Natalka [10]

Option D:

ΔCAN ≅ ΔWNA by SAS congruence rule.

Solution:

Given data:

m∠CNA = m∠WAN and CN = WA

To prove that ΔCAN ≅ ΔWNA:

In ΔCAN and ΔWNA,

CN = WA (given side)

∠CNA = ∠WAN (given angle)

NA = NA (reflexive side)

Therefore, ΔCAN ≅ ΔWNA by SAS congruence rule.

Hence option D is the correct answer.

4 0

3 years ago