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Ludmilka [50]
3 years ago
11

For what value of k, the zeroes of x2 + kx + 12 will differ by 1?

Mathematics
1 answer:
asambeis [7]3 years ago
8 0

Let <em>a</em> and <em>b</em> be the zeroes of <em>x</em>² + <em>kx</em> + 12 such that |<em>a</em> - <em>b</em>| = 1.

By the factor theorem, we can write the quadratic in terms of its zeroes as

<em>x</em>² + <em>kx</em> + 12 = (<em>x</em> - <em>a</em>) (<em>x</em> - <em>b</em>)

Expand the right side and equate the coefficients:

<em>x</em>² + <em>kx</em> + 12 = <em>x</em>² - (<em>a</em> + <em>b</em>) <em>x</em> + <em>ab</em>

Then

<em>a</em> + <em>b</em> = -<em>k</em>

<em>ab</em> = 12

The condition that |<em>a</em> - <em>b</em>| = 1 has two cases, so without loss of generality assume <em>a</em> > <em>b</em>, so that |<em>a</em> - <em>b</em>| = <em>a</em> - <em>b</em>.

Then if <em>a</em> - <em>b</em> = 1, we get <em>b</em> = <em>a</em> - 1. Substitute this into the equations above and solve for <em>k</em> :

<em>a</em> + (<em>a</em> - 1) = -<em>k</em>   →   2<em>a</em> = 1 - <em>k</em>   →   <em>a</em> = (1 - <em>k</em>)/2

<em>a</em> (<em>a</em> - 1) = 12   →   (1 - <em>k</em>)/2 • ((1 - <em>k</em>)/2 - 1) = 12

→   (1 - <em>k</em>)²/4 - (1 - <em>k</em>)/2 = 12

→   (1 - <em>k</em>)² - 2 (1 - <em>k</em>) = 48

→   (1 - 2<em>k</em> + <em>k</em>²) - 2 (1 - <em>k</em>) = 48

→   <em>k</em>² - 1 = 48

→   <em>k</em>² = 49

→   <em>k</em> = ± √(49) = ±7

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Answer:

The answer is below

Step-by-step explanation:

a) Given that the number of sample (n) = 300, therefore since n > 30, the distribution of the sample means is going to be normally distributed.

b) The mean of the distribution of sample means (also known as the Expected value of M) is equal to the population mean μ.

\mu_x=\mu=np=300*0.39=117

c) The standard deviation of the distribution of sample means is called the Standard Error of M, it is given by:

\sigma_x=\sqrt{np(1-p)} =\sqrt{300*0.39(1-0.39)} =8.44

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Find the volume of the largest rectangular box in the first octant with three faces in the coordinate planes and one vertex in t
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Answer: The volume of largest rectangular box is 4.5 units.

Step-by-step explanation:

Since we have given that

Volume = xyz

with subject to x+2y+3z=9

So, let z=\dfrac{9-x-2y}{3}

So, Volume becomes,

V=xyz\\\\V=xy(\dfrac{9-x-2y}{3})\\\\V=\dfrac{9xy-x^2y-2xy^2}{3}

Partially derivative wrt x and y we get that

9-2x-2y=0\implies 2x+2y=9\\\\and\\\\9-x-4y=0\implies x+4y=9

By solving these two equations, we get that

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So, z=\dfrac{9-x-2y}{3}=\dfrac{9-3-3}{3}=\dfrac{3}{3}=1

So, Volume of largest rectangular box would be

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Question 24 Multiple Choice Worth 1 points)
hammer [34]

Given:

The system of equations is:

Line A: y=x-4

Line B: y=3x+4

To find:

The solution of given system of equations.

Solution:

We have,

y=x-4              ...(i)

y=3x+4           ...(ii)

Equating (i) and (ii), we get

x-4=3x+4

-4-4=3x-x

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Divide both sides by 2.

-4=x

Substituting x=-4 in (i), we get

y=-4-4

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The solution of system of equations is (-4,-8).

Now verify the solution by substituting x=-4, y=-8 in the given equations.

-8=-4-4

-8=-8

This statement is true.

Similarly,

-8=3(-4)+4

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This statement is also true.

Therefore, (-4,-8) is a solution of the given system of equations, because the point satisfies both equations. Hence, the correct option is C.

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