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2 years ago

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what are the solutions of 4x^2-8x+5=0 A. x=2+i/2 or x=2-i/2. B. x=1+i/2 or x=1-i/2 C. x=1+i or x=1-i D. x=2+i or x=2-i

1 answer:

rewona [7]2 years ago

5 0

The correct answer is Option A.

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Answer this true or false question please:4x-1<2x+7 when x =0

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True!
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3 years ago

The sum of two terms of gp is 6 and that of first four terms is 15/2.Find the sum of first six terms.

Gnoma [55]

Given:

The sum of two terms of GP is 6 and that of first four terms is $\dfrac{15}{2}.$

To find:

The sum of first six terms.

Solution:

We have,

$S_2=6$

$S_4=\dfrac{15}{2}$

Sum of first n terms of a GP is

$S_n=\dfrac{a(1-r^n)}{1-r}$ ...(i)

Putting n=2, we get

$S_2=\dfrac{a(1-r^2)}{1-r}$

$6=\dfrac{a(1-r)(1+r)}{1-r}$

$6=a(1+r)$ ...(ii)

Putting n=4, we get

$S_4=\dfrac{a(1-r^4)}{1-r}$

$\dfrac{15}{2}=\dfrac{a(1-r^2)(1+r^2)}{1-r}$

$\dfrac{15}{2}=\dfrac{a(1+r)(1-r)(1+r^2)}{1-r}$

$\dfrac{15}{2}=6(1+r^2)$ (Using (ii))

Divide both sides by 6.

$\dfrac{15}{12}=(1+r^2)$

$\dfrac{5}{4}-1=r^2$

$\dfrac{5-4}{4}=r^2$

$\dfrac{1}{4}=r^2$

Taking square root on both sides, we get

$\pm \sqrt{\dfrac{1}{4}}=r$

$\pm \dfrac{1}{2}=r$

$\pm 0.5=r$

Case 1: If r is positive, then using (ii) we get

$6=a(1+0.5)$

$6=a(1.5)$

$\dfrac{6}{1.5}=a$

$4=a$

The sum of first 6 terms is

$S_6=\dfrac{4(1-(0.5)^6)}{(1-0.5)}$

$S_6=\dfrac{4(1-0.015625)}{0.5}$

$S_6=8(0.984375)$

$S_6=7.875$

Case 2: If r is negative, then using (ii) we get

$6=a(1-0.5)$

$6=a(0.5)$

$\dfrac{6}{0.5}=a$

$12=a$

The sum of first 6 terms is

$S_6=\dfrac{12(1-(-0.5)^6)}{(1+0.5)}$

$S_6=\dfrac{12(1-0.015625)}{1.5}$

$S_6=8(0.984375)$

$S_6=7.875$

Therefore, the sum of the first six terms is 7.875.

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If the price of address is 40 before taxes added on and taxes 20% what will the final price of the dress be?

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3 years ago

Please help me with this question!!!!!

Naddika [18.5K]

Answer:

Equation of line in slope-intercept form that passes through (4, -8) and is perpendicular to the graph $y= \frac {2}{5} x - 3$ is below

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Step-by-step explanation:

Slope of the equation $y= \frac{2}{5} x -3$ is $m_1 = \frac{2}{5}$

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$m_2 = - \frac {1}{m_1} = - \frac {5}{2}$

Equation of line in point slope form is given as

$y-y_1=m_2(x-x_1)$

Here (x1, y1) = (4, -8)

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

Simplifying it further

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