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3 years ago

Which method is most efficient method to use to solve 2x^2+4x-7=0

Mathematics

1 answer:

Natali5045456 [20]3 years ago

4 0

Answer:

Use the quadratic formula

Step-by-step explanation:

Use the quadratic formula

For a quadratic function of the form:

$ax ^ 2 + bx + c$

Where a, b and c are the real coefficients of the polynomial

Then, for

$2x^2+4x-7=0\\a = 2\\b = 4\\c = -7$

The solutions are:

$x_1 = \frac{-b+\sqrt{b^2-4ac}}{2a}\\\\x_2 = \frac{-b-\sqrt{b^2-4ac}}{2a}$

$x_1 = \frac{-4+\sqrt{4^2-4(2)(-7)}}{2(2)}\\\\x_2 = \frac{-4-\sqrt{4^2-4(2)(-7)}}{2(2)}\\\\x_1 = \frac{-2+3\sqrt{2}}{2}\\\\x_2 = \frac{-2-3\sqrt{2}}{2}$

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joja [24]

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3 years ago

A counter top is 18 feet long and 3 feet wide. What is the area of the counter top in square meters? Use the conversion 1 foot =

podryga [215]

Answer:

Area of the counter top is $5.02\ m^2$ .

Step-by-step explanation:

Given:

Length of the Counter top = 18 feet

Width of the counter top = 3 feet

We need to find the area of the counter top is square meter;

Solution:

Now we need to find the area of the counter top is square meter.

But given data is in feet so we will first convert feet into meters.

1 foot = 0.305 meter.

So 18 feet = Number of meters in 18 feet.

By Using Unitary method we get;

Number of meters in 18 feet = $18\times 0.305 = 5.49\ m$

Length of the Counter top = 5.49 m

Also 3 feet = Number of meters in 3 feet.

Again Using Unitary method we get;

Number of meters in 3 feet = $3\times 0.305 = 0.915\ m$

Width of the counter top = 0.915 m

Now we know that;

Area of the counter top can be calculated by multiplying Length of the counter top with width of the counter top.

framing in equation form we get;

Area of the counter top = $5.49\times 0.915 = 5.0233\ m^2$

Rounding up to 2 decimals we get;

Area of the counter top = $5.02\ m^2$

Hence Area of the counter top is $5.02\ m^2$ .

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4 years ago

5 1/2 feets in a yard

zhannawk [14.2K]

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3 years ago

A members-only speaker series allows people to join for $19 and then pay $4 for every

Lera25 [3.4K]

Answer: 3

Step-by-step explanation:

Let's create a model first.

The initial fee is $19 (this is our y intercept or b)

And the pay per is $4 (this is our variable or m)

y=mx+b

y= 4x+19

To find out what the maximum number of events someone can attend for $31, we plug in different number for the x value until it's less than or equal to $31

In this case, plugging in 3 for x gives us exactly $31

y=4(3)+19= 31

6 0

3 years ago

You always need some time to get up after the alarm has rung. You get up from 10 to 20 minutes later, with any time in that inte

Mama L [17]

Answer:

a) P(x<5)=0.

b) E(X)=15.

c) P(8<x<13)=0.3.

d) P=0.216.

e) P=1.

Step-by-step explanation:

We have the function:

$f(x)=\left \{ {{\frac{1}{10},\, \, \, 10\leq x\leq 20 } \atop {0, \, \, \, \, \, \, otherwise }} \right.$

a) We calculate the probability that you need less than 5 minutes to get up:

$P(x$

Therefore, the probability is P(x<5)=0.

b) It takes us between 10 and 20 minutes to get up. The expected value is to get up in 15 minutes.

E(X)=15.

c) We calculate the probability that you will need between 8 and 13 minutes:

$P(8\leq x\leq 13)=P(10\leqx\leq 13)\\\\P(8\leq x\leq 13)=\int_{10}^{13} f(x)\, dx\\\\P(8\leq x\leq 13)=\int_{10}^{13} \frac{1}{10} \, dx\\\\P(8\leq x\leq 13)=\frac{1}{10} \cdot [x]_{10}^{13}\\\\P(8\leq x\leq 13)=\frac{1}{10} \cdot (13-10)\\\\P(8\leq x\leq 13)=\frac{3}{10}\\\\P(8\leq x\leq 13)=0.3$

Therefore, the probability is P(8<x<13)=0.3.

d) We calculate the probability that you will be late to each of the 9:30am classes next week:

$P(x>14)=\int_{14}^{20} f(x)\, dx\\\\P(x>14)=\int_{14}^{20} \frac{1}{10} \, dx\\\\P(x>14)=\frac{1}{10} [x]_{14}^{20}\\\\P(x>14)=\frac{6}{10}\\\\P(x>14)=0.6$

You have 9:30am classes three times a week. So, we get:

$P=0.6^3=0.216$

Therefore, the probability is P=0.216.

e) We calculate the probability that you are late to at least one 9am class next week:

$P(x>9.5)=\int_{10}^{20} f(x)\, dx\\\\P(x>9.5)=\int_{10}^{20} \frac{1}{10} \, dx\\\\P(x>9.5)=\frac{1}{10} [x]_{10}^{20}\\\\P(x>9.5)=1$

Therefore, the probability is P=1.

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3 years ago