How many times does 21 go into 221 evenly

Solve the following equation by factoring:9x^2-3x-2=0

olya-2409 [2.1K]

Answer:

The two roots of the quadratic equation are

$x_1= - \frac{1}{3} \text{ and } x_2= \frac{2}{3}$

Step-by-step explanation:

Original quadratic equation is $9x^{2}-3x-2=0$

Divide both sides by 9:

$x^{2} - \frac{x}{3} - \frac{2}{9}=0$

Add $\frac{2}{9}$ to both sides to get rid of the constant on the LHS

$x^{2} - \frac{x}{3} - \frac{2}{9}+\frac{2}{9}=\frac{2}{9}$ ==> $x^{2} - \frac{x}{3}=\frac{2}{9}$

Add $\frac{1}{36}$ to both sides

$x^{2} - \frac{x}{3}+\frac{1}{36}=\frac{2}{9} +\frac{1}{36}$

This simplifies to

$x^{2} - \frac{x}{3}+\frac{1}{36}=\frac{1}{4}$

Noting that (a + b)² = a² + 2ab + b²

If we set a = x and b = $\frac{1}{6}\right)$ we can see that

$\left(x - \frac{1}{6}\right)^2$ = $x^2 - 2.x. (-\frac{1}{6}) + \frac{1}{36} = x^{2} - \frac{x}{3}+\frac{1}{36}$

So

$\left(x - \frac{1}{6}\right)^2=\frac{1}{4}$

Taking square roots on both sides

$\left(x - \frac{1}{6}\right)^2= \pm\frac{1}{4}$

So the two roots or solutions of the equation are

$x - \frac{1}{6}=-\sqrt{\frac{1}{4}}$ and $x - \frac{1}{6}=\sqrt{\frac{1}{4}}$

$\sqrt{\frac{1}{4}} = \frac{1}{2}$

So the two roots are

$x_1=\frac{1}{6} - \frac{1}{2} = -\frac{1}{3}$

and

$x_2=\frac{1}{6} + \frac{1}{2} = \frac{2}{3}$

7 0

1 year ago

A dentist polls his patients and finds that 83 percent brush their teeth at least twice a day, 47 percent floss daily, and 19 pe

puteri [66]

Answer:

The correct option is B. 23%

Step-by-step explanation:

Let the event that patient brushes his teeth at least twice a day is denoted by A

So, P(A) = 0.83

Let the event that patient flosses daily is denoted by B

So, P(B) = 0.47

Now, it is given that 19 percent patients brush at least twice a day and floss daily.

⇒ P(A and B) = 0.19

Now, we need to find conditional probability of occurring event B given A has occurred.

$\implies P(B|A) =\frac{P(A\: and\: B)}{P(A)}\\\\\implies P(B|A) = \frac{0.19}{0.83}\\\\\implies P(B|A) = 0.2289\approx 0.23$

Hence, Nearest required percentage = 23%

Therefore, The correct option is B. 23%

4 0

2 years ago

Read 2 more answers

Plzz help me with this question

bixtya [17]

Answer:

x = 5

Step-by-step explanation:

We need to find the value of x in this case.

For this, we need to consider that the triangles are similar. Now, we can find it as follows :

$\dfrac{12}{3}=\dfrac{20}{x}\\\\x=\dfrac{20\times 3}{12}\\\\x=5$

So, the value of x is equal to 5.

6 0

2 years ago

Bruce has a bottle that contains 60% lemon juice and the rest water. The bottle has 1 liter of water.

Cloud [144]

part A:
Let
t = total the liquid in the bottle including lemon juice and water
so t = lemon juice + water ( w = water, l = lemon juice) so t = l + w
but the bottle has 1 liter of water. and 60% lemon juice
contains 60% lemon juice = 0.6, so l = 0.6t and w(water ) = 1 liter
t = l + w
substitute l = 0.6t and w = 1 into t = l + w
now you have equation
t = 0.6t + 1

part B:
from part A, you have equation t = 0.6t +1
solve for t
t = 0.6t +1
subtract 0.6t on both sides
t - 0.6t = 0.6t - 0.6t + 1
simplify
0.4t = 1
divide both sides by 0.4
0.4t/0.4 = 1/ 0.4
simplify
t = 2.5

2.5 liters is total including lemon juice and water
2.5 - 1(1 liter of water) = 1.5 1 liter of lemon juice

8 0

3 years ago

Read 2 more answers

Write the ratio that compares 1 1/2 cups of flour to 2 eggs.

Sholpan [36]

Answer:

Step-by-step explanation:

A ratio is comparison between two values in math

1.5 cups of flour : 2 eggs

1.5 cups of flour to 2 eggs

$\frac{1.5 cups of flour}{2 eggs }$

6 0

2 years ago