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anzhelika [568]

3 years ago

11

How many solutions are there for the equation 7x^2-9x=3

1 answer:

Nadusha1986 [10]3 years ago

6 0

Answer:

2

Step-by-step explanation:

For this equation, you want to work out the discriminant (Δ), which is equal to b²-4ac. If Δ>0, there are 2 solutions, if Δ=0, there is one solution, and if Δ<0, there are no solutions. This can be explained with the quadratic formula.

For this problem, you want to convert the question into ax²+bx+c=0 formula.

This makes the question 7x²-9x-3. a here is 7, b is -9, and c is -3.

Substituting these values into the discriminant formula gives (-9)²-4(7×-3), which can be simplified to 81-4×-21, or 81+84. This equals 165 which is > 0, so there are 2 answers.

**This involves using discriminants and the quadratic formula, which you may wish to revise. I'm always happy to help!

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Solve the proportion 2/5=x/3

Slav-nsk [51]

Answer:

1.2

Step-by-step explanation:

1.2/3 is 40 percent

2/5 is 40 percent

used guess and check took me 1 minute

8 0

3 years ago

When do u evaluate exponents in the order of operations?? <br> Pls help I got 9 minutes to do this

olga2289 [7]

Answer:

2nd

Step-by-step explanation:

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3 0

3 years ago

Use technology to approximate the solution(s) to the system of equations to the nearest tenth of a unit. f(x) = 3^x-7 g(x) = 2 l

Gemiola [76]

Answer:

(.5 , 0) (7.8 , 2.4)

Step-by-step explanation:

The solution to a system of equations is when they cross each other on a graph.

When this is graphed you case use the trace and zoom in tools to find where they are solutions at.

5 0

4 years ago

How can you be sure that you have listed all of the proper factors of a number

Alexxandr [17]

Do the math of all multplications facts and see if there is more
or look it up and see if you left some out

5 0

4 years ago

What should a size of a sample be in order to have a margin of error of 4% for a 90% confidence level from a population with a s

vagabundo [1.1K]

Answer:

We need a sample size of 2,071,800 or higher.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$

Now, we find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

In this problem:

We need a sample size of n or higher, when $M = 0.04, \sigma = 35$ . So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.04 = 1.645*\frac{35}{\sqrt{n}}$

$0.04\sqrt{n} = 1.645*35$

$0.04\sqrt{n} = 57.575$

$\sqrt{n} = 1439.375$

$\sqrt{n}^{2} = (1439.375)^{2}$

$n = 2,071,800$

We need a sample size of 2,071,800 or higher.

6 0

3 years ago