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0 votes
0 answers
75 views

How is this property of definite integral derived?

The property: $$ \int_a^b f(x) \, dx=\int_a^b f(a+b-x) \, dx $$ Derivation given in my textbook: Let $t = a+b-x$. Then $dt = -d x$. When $x=a, t=b$ and when $x=b, t=a$. Therefore, $$ \begin{aligned} \...
Nitish's user avatar
  • 33
1 vote
1 answer
168 views

Question on the bounds of definite integration during a substitution

Apologies if this question is rather elementary. I seem to still misunderstand a few things about how bounds change during substitutions still. I was taught in calc II that to perform a substitution, ...
Max0815's user avatar
  • 3,515
2 votes
2 answers
59 views

Find $\int_{\left(C\right)}xy{\rm d}x+y^{2}{\rm d}y$ with $\left(C\right)$ bound by $y\geq 0,x^{2}+y^{2}=4\left({\rm clockwise}\right).$

Prob. Find $\int_{\left ( C \right )}xy{\rm d}x+ y^{2}{\rm d}y$ with $\left ( C \right )$ closed by the path $y\geq 0, x^{2}+ y^{2}= 4\left ( {\rm clockwise} \right ).$ My attempt: $\int_{\left ( C \...
user avatar
2 votes
3 answers
99 views

How to evaluate $\iint_R \sin(\frac{y-x}{y+x})dydx$ with Jacobian substitution?

I want to calculate this integral with substitution $x=u+v , \ y=u-v$: $$\iint_R \sin\left(\frac{y-x}{y+x}\right)dydx$$ $$R:= \{(x,y):x+y≤\pi, y≥0,x≥0\}$$ but I don't know how to set new bounds for $...
Amir reza Riahi's user avatar
11 votes
3 answers
538 views

Is it necessary to write limits for a substituted integral?

To solve the following integral, one can use u-substitution: $$\int_2^3 \frac{9}{\sqrt[4]{x-2}} \,dx,$$ With $u = \sqrt[4]{x-2}$, our bounds become 0 and 1 respectively. Thus, we end up with the ...
Lord Kanelsnegle's user avatar