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3 years ago

Find the equation of the axis of symmetry and the coordinates of the vertex of the graph of y=4x^2+5x-1

Mathematics

1 answer:

Ivanshal [37]3 years ago

4 0

Answer:

Axis of symmetry: $x=-\frac{5}{8}$

Vertex: $(-\frac{5}{8},-2\frac{9}{16})$

Step-by-step explanation:

The given quadratic equation is

$y=4x^2+5x-1$

By comparing to the general quadratic function; $y=ax^2+bx+c$

We have a=4,b=5,c=-1

The equation of the axis of symmetry is given by the formula;

$x=-\frac{b}{2a}$

We got this formula by completing the square on the general quadratic function.

We substitute a=4 and b=5 to obtain;

$x=-\frac{5}{2(4)}$

$x=-\frac{5}{8}$
is the axis of symmetry.

To find the y-value of the vertex, we put $x=-\frac{5}{8}$ into the function to obtain;

$y=4(-\frac{5}{8})^2+5(-\frac{5}{8})-1$

$y=4(-\frac{5}{8})^2+5(-\frac{5}{8})-1$

$y=-\frac{41}{16}$

The vertex of the given function is $(-\frac{5}{8},-2\frac{9}{16})$

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694

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2 years ago

A boulder falls off the top of a cliff during a storm. The cliff is 90 feet high.

andreev551 [17]

Answer:

It will take the boulder approximately 4.28 seconds to hit the road

Step-by-step explanation:

The given height of the cliff from which the boulder falls, h = 90 feet

The equation that can be used to find the time it takes the boulder to fall is h = u·t + (1/2)·g·t²

Where;

h = The height of the cliff = 90 ft.

u = The initial velocity of the boulder = 0 m/s (The boulder is assumed to be at rest when it falls)

g - The acceleration due to gravity ≈ 9.81 m/s²

t = How long it will take for the boulder to hit the road below

Plugging in the values gives;

90 = 0 × t + (1/2)×9.81×t² = 4.905·t²

∴ t = √(90/4.905) ≈ 4.28

The time it takes the boulder to hit the road, t ≈ 4.28 seconds.

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2 years ago

Next Save 5 A student earns $70 over the summer. He spends of the total amount on movies. He then spends į of the remaining mone

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2 years ago

Marine scientists categorize signature whistles of bottlenose dolphins by typelong dash—type a, type b, type c, etc. In one s

r-ruslan [8.4K]

Answer:

The 95% confidence interval for the true proportion of bottlenose dolphin signature whistles that are type a whistles is (0.4687, 0.6123).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

$n = 185, \pi = \frac{100}{185} = 0.5405$

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.5405 - 1.96\sqrt{\frac{0.5405*0.4595}{185}} = 0.4687$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.5405 + 1.96\sqrt{\frac{0.5405*0.4595}{185}} = 0.6123$

The 95% confidence interval for the true proportion of bottlenose dolphin signature whistles that are type a whistles is (0.4687, 0.6123).

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2 years ago

How do I do question 9 & 11? Please help thank you!

Novay_Z [31]

<h2>9.</h2><h3>Given</h3>

sphere with radius 15 cm

linear approximation to the volume when the radius increases 0.4 cm

<h3>Solution</h3>

The equation for volume of a sphere is

... V = (4/3)π·r³

Differentiating gives

... dV = 4π·r²·dr

Filling in the given numbers gives

... change in volume ≈ 4π·(15 cm)²·(0.4 cm)

... = 360π cm³ ≈ 1130.97 cm³ . . . . . . volume of layer 4mm thick

<h2>11.</h2><h3>Given</h3>

an x by x by 2x cuboid with surface area 129.6 cm²
rate of change of x is 0.01 cm/s

rate of change of volume

<h3>Solution</h3>

The area is that of two cubes of dimension x joined together. The area of each such cube is 6x², but the two joined faces don't count in the external surface area. Thus the area of the cuboid is 10x².

The volume of the cuboid is that of two cubes joined, so is 2x³. Then the rate of change of volume is

... dV/dt = (d/dt)(2x³) = 6x²·dx/dt

We know x² = A/10, where A is the area of the cuboid, so the rate of change of volume is ...

... dV/dt = (6/10)A·dx/dt = 0.6·(129.6 cm²)(0.01 cm/s)

... dV/dt = 0.7776 cm³/s

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2 years ago