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Integral method available**.

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Obviously, when a<=0, this integral is divergent.

So we're only talking about the case of a>0.

First, use the partial integration method to eliminate x 2.

x*e^(-ax^2)/2a + 1/2a)*∫e^(-ax^2)dx

The first half of the equation can be calculated directly to result in 0, and the remaining integral (not looking at the coefficient) e (-ax 2)dx

It's a Poisson integral, I can't write the original function, but I can calculate it, the method is very long, if you are interested, you can go to the Internet to find the method, I won't write it here, I'll tell you the answer directly.

Multiply by the coefficient, and the final result is (1 4) * a 3).

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It's something like the value of wealth.

Option D.

In fact, the integration region of the original integral is.

g:0 2,0 r cos, or g:0 2,0 r rcos, (the inequality on the right is x +y x, plotted) gives g:0 y (x-x), 0 x 1, and the cumulative integral is d.

d draws the integral region in the polar coordinate system, and converts it to the Cartesian coordinate system is the upper semicircle of the x-axis from 0 to 1, the integrand is f(x,y), and the region is the drawn semicircle.

The product sum is different, sin5xsin7x=-1 2[cos12x-cos2x], so the original formula =-1 2 (cos12x-cos2x)=-1 2(1 12*sin12x-1 2*sin2x)+c=-1 24*sin12x+1 4*sin2x+c.

First of all, you need to know that (tanx) 2+1=(secx) 2 ; Then the result 1 2 (the absolute value of secxtanx+ln(secx+tanx)) + c can be obtained by using the method of integrating the sedan with the sail stupid hole in steps

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