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4 years ago

Calcula el valor de la serie: S = 12 + 22 + 32 +42 + ... 172

Mathematics

1 answer:

Doss [256]4 years ago

6 0

Answer:

S = 1564

Step-by-step explanation:

S = 12 + 22 + 32 + .. + 172

= 12 + (12+10) + (12+20) + .. + (12+160)

= 10(1 + 2 + .. + 16) + 12×17

= 10×16×17/2 + 12×17

= 1360 + 204

= 1564

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Use the Trapezoidal Rule, the Midpoint Rule, and Simpson's Rule to approximate the given integral with the specified value of n.

Vera_Pavlovna [14]

Split up the integration interval into 4 subintervals:

$\left[0,\dfrac\pi8\right],\left[\dfrac\pi8,\dfrac\pi4\right],\left[\dfrac\pi4,\dfrac{3\pi}8\right],\left[\dfrac{3\pi}8,\dfrac\pi2\right]$

The left and right endpoints of the $i$ -th subinterval, respectively, are

$\ell_i=\dfrac{i-1}4\left(\dfrac\pi2-0\right)=\dfrac{(i-1)\pi}8$

$r_i=\dfrac i4\left(\dfrac\pi2-0\right)=\dfrac{i\pi}8$

for $1\le i\le4$ , and the respective midpoints are

$m_i=\dfrac{\ell_i+r_i}2=\dfrac{(2i-1)\pi}8$

Trapezoidal rule

We approximate the (signed) area under the curve over each subinterval by

$T_i=\dfrac{f(\ell_i)+f(r_i)}2(\ell_i-r_i)$

so that

$\displaystyle\int_0^{\pi/2}\frac3{1+\cos x}\,\mathrm dx\approx\sum_{i=1}^4T_i\approx\boxed{3.038078}$

Midpoint rule

We approximate the area for each subinterval by

$M_i=f(m_i)(\ell_i-r_i)$

so that

$\displaystyle\int_0^{\pi/2}\frac3{1+\cos x}\,\mathrm dx\approx\sum_{i=1}^4M_i\approx\boxed{2.981137}$

Simpson's rule

We first interpolate the integrand over each subinterval by a quadratic polynomial $p_i(x)$ , where

$p_i(x)=f(\ell_i)\dfrac{(x-m_i)(x-r_i)}{(\ell_i-m_i)(\ell_i-r_i)}+f(m)\dfrac{(x-\ell_i)(x-r_i)}{(m_i-\ell_i)(m_i-r_i)}+f(r_i)\dfrac{(x-\ell_i)(x-m_i)}{(r_i-\ell_i)(r_i-m_i)}$

so that

$\displaystyle\int_0^{\pi/2}\frac3{1+\cos x}\,\mathrm dx\approx\sum_{i=1}^4\int_{\ell_i}^{r_i}p_i(x)\,\mathrm dx$

It so happens that the integral of $p_i(x)$ reduces nicely to the form you're probably more familiar with,

$S_i=\displaystyle\int_{\ell_i}^{r_i}p_i(x)\,\mathrm dx=\frac{r_i-\ell_i}6(f(\ell_i)+4f(m_i)+f(r_i))$

Then the integral is approximately

$\displaystyle\int_0^{\pi/2}\frac3{1+\cos x}\,\mathrm dx\approx\sum_{i=1}^4S_i\approx\boxed{3.000117}$

Compare these to the actual value of the integral, 3. I've included plots of the approximations below.

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3 years ago

One angle of an isosceles triangle measures 138°. Which other angles could be in that isosceles triangle?

BartSMP [9]

Answer:

2 21 degree angles

Step-by-step explanation:

An isosoles triangle has two congruent angles and every triangle's sum of interior angles equals 180 degrees. 138*2>180, so the 138 degree angle cannot be congruent to any of the other angles. Therefore:

180=138+2x

42=2x

21 degrees=x

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3 years ago

What is the factores form of (2x^2+11x-40)?

Cerrena [4.2K]

${2x}^{2} + 11x - 40 \\ = (2x - 5)(x + 8)$

Hope this helps. - M

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3 years ago

Find the equation of the line described.

Lunna [17]

Answer:

y = -1/3x + 4

Step-by-step explanation:

y = 3x +5

current slope m is 3, perpendicular is opposite inverse which is -1/3

Passing through (6,2):

y = mx + b

2 = -1/3(6) + b

2 = -2 + b

b = 4

Use the perpendicular m = -1/3 and b = 4 to form equation of line:

y = mx + b

y = -1/3x + 4

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3 years ago

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krok68 [10]

The answer this problem is -247

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3 years ago