Let $f(x)=e^{-1/x}$ . Then $f'(x)=\frac1{x^2}e^{-1/x}>0$ for all $x\ge2$ , so $f$ is strictly increasing. As $x\to\infty$ , $e^{-1/x}\to e^0=1$ , so $f$ is bounded above by 1. This is to say,

$e^{-1/x}$

and the integral of $\frac1{x^2}$ converges over the same domain, so this integral must also converge by comparison.

We have, by setting $y=-\frac1x$ ,

$\displaystyle\int_2^\infty\frac{e^{-1/x}}{x^2}\,\mathrm dx=\int_{-1/2}^0e^y\,\mathrm dy=e^0-e^{-1/2}=1-\frac1{\sqrt e}$

8 0

2 years ago

Identify each matrix A such that A^2 has identical diagonal elements?

Maksim231197 [3]

Answer:

The correct matrices are:

Matrix:

7 1 5

1 5 7

5 7 1

all diagonal elements of A^2 are: 7^2 + 1^2 + 5^2

Matrix:

9 18 27

27 -9 18

18 27 9

all diagonal elements of A^2 are: 9^2 + 27*18 + 18*27 or (-9)^2

Matrix:

8 1 6

6 8 1

1 6 8

all diagonal elements of A^2 are: 8^2 + 6*1 + 1*6

6 0

3 years ago

If 12 cows produce 70 gallons of milk, how many gallons would 42 cows produce?

omeli [17]

Answer:

245

Step-by-step explanation:

-6 cows produce 35 gallons

6 x 7 =42

so 7 x 35 = 245

8 0

3 years ago