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2 years ago

15 / √31 - 4

Mathematics

1 answer:

NeX [460]2 years ago

6 0

Answer:

$\frac{15}{ \sqrt{31} - 4}} = \sqrt{31} + 4$

Step-by-step explanation:

$\frac{15}{\sqrt{31} - 4}\\\\=\frac{15}{\sqrt{31} - 4} \times \frac{\sqrt{31} + 4}{\sqrt{31}+ 4} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ rationalizing \ the \ denominator \ ]\\\\=\frac{15( \sqrt{31} + 4 )}{(\sqrt{31})^2 - (4)^2} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ (a-b)(a+b) = a^2 - b^2 \ ]\\\\=\frac{15 ( \sqrt{31} + 4)}{31 - 16}\\\\=\frac{15 (\sqrt{31} + 4)}{15}\\\\= \sqrt{31} + 4$

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koban [17]

Answer:

a=42°

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Step-by-step explanation:

the sum of angles on a triangle is 180°

18+120+a=180

138+a=180

a=180-138

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a+b=180 because a ans b are linear pair of angles.

Definiton:A linear pair of angles is formed when two lines intersect. Two angles are said to be linear if they are adjacent angles formed by two intersecting lines. The measure of a straight angle is 180 degrees, so a linear pair of angles must add up to 180 degrees.

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3 years ago

Find n for which the nth iteration by the Bisection Method guarantees to approximate the root of f(x) = 2x^2 − 3x − 2 on [−2, 1]

Lady_Fox [76]

Answer:

n = 29 iterations would be enough to obtain a root of $f(x)=2x^2-3x-2$ that is at most $10^{-8}$ away from the correct solution.

Step-by-step explanation:

You can use this formula which relates the number of iterations, n, required by the bisection method to converge to within an absolute error tolerance of ε starting from the initial interval (a, b).

$n\geq \frac{log(\frac{b-a}{\epsilon} )}{log(2)}$

We know

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Thus, n = 29 iterations would be enough to obtain a root of $f(x)=2x^2-3x-2$ that is at most $10^{-8}$ away from the correct solution.

You can prove this result by doing the computation as follows:

From the information given we know:

$f(x)=2x^2-3x-2$
$\epsilon = 10^{-8}$

This is the algorithm for the Bisection method:

Find two numbers a and b at which f has different signs.
Define $c=\frac{a+b}{2}$
If $b-c\leq \epsilon$ then accept c as the root and stop
If $f(a)f(c)\leq 0$ then set c as the new b. Otherwise, set c as the new a. Return to step 1.