Hints: UNT Integration Bee

Hints for Past Problems

This page is under construction; the links to solutions do not work yet.

1989:

Write the integrand as a sum of (negative) powers of x. Solution
Substitution. Solution
Substitute u = x + 4, then multiply out. Solution
Substitute u = - x^2, then integrate by parts. Solution
Complete the square, then use trigonometric substitution. Solution
Substitute u for the integrand,
then use partial fraction decomposition.
Solution
Note sech^2 in integrand; IBP. Solution
IBP with u = sec^3; use trig. identity to reduce to sec^3 integral.
IBP again with u = sec.
Solution
Substitute u = arcsin x. Solution
Multiply numerator and denominator by (1 - cos x);
expand numerator.
Solution
Trigonometric substitution; double-angle formulas. Solution
Partial fraction decomposition. Solution

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1990:

Substitution. Solution
Expand and integrate term by term. Solution
Substitute u = x - 1; expand and integrate term by term. Solution
IBP with u = x^2. Solution
Substitute u = cos x; then IBP. Solution
Complete the square, then use substitution. Solution
Substitute u = x^(3/2); IBP. Solution
Multiply numerator and denominator by (1 - sin x);
expand numerator.
Solution
Substitute u = tan(x/2). Solution
IBP twice; solve for original. Solution
Trigonometric substitution. Solution
Partial fraction decomposition. Solution

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1991:

Expand and integrate term by term. Solution
Substitution. Solution
Substitute u = x + 3; expand; integrate term by term. Solution
IBP with u = x^2. Solution
Substitute u = x^3; complete square;
trigonometric substitution.
Solution
Trigonometric substitution. Solution
Multiply numerator and denominator by (1 - cos x);
expand; integrate term by term.
Solution
IBP with u = log x; partial fraction decomposition. Solution
Partial fraction decomposition. Solution
Substitute y = x + 1; split integrand into two terms;
IBP one of them with u = exp; miraculous cancellation!
Solution
Substitute u = x^(1/2); partial fraction decomposition. Solution
IBP with u = log(1 + x^2),
then partial fraction decomposition.
Solution
Substitute u = sin x; use a trig. identity;
expand; integrate term by term.
Solution
IBP twice; solve for original integral. Solution

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1992:

Expand; integrate term by term. Solution
Substitute u = log x. Solution
Substitute u = (x-1)^(1/2); then trig. substitution. Solution
Substitute u = x^(1/2); IBP. Solution
Substitute u = x^4; partial fraction decomposition. IBP. Solution
Multiply numerator and denominator by (sec x - 1);
expand; integrate term by term.
Solution
IBP with u = (arcsin x)^2; substitute y = arcsin x. Solution
Substitute x = sin t; then substitute u = tan(t/2). Solution
Substitute x = u^6; use long division. Solution

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1993:

Long division. Solution
Use trig. identity, then IBP with u = x. Solution
IBP with u = log x. Solution
Substitute u = sin x; cancel factors. Solution
Substitute u = e^x. Solution
Substitute u = tan x; partial fraction decomposition. Solution
Separate integrand into 2 terms. IBP each:
One with u = x; other with u = exp(x^2).
Solution
Multiply numerator and denominator by (x-1)^(1/2);
substitute x = sec t.
Solution

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1994:

e^2 is a constant. Solution
Use trig. identity. Solution
IBP with u = arctan x. Solution
Partial fraction decomposition. Solution
Substitute u = 1 + x^(3/2). Solution
Write in terms of sin and cos; separate into 2 terms;
IBP each, one with u = x; other with u = (sin x)^(1/2);
miraculous cancellation!
Solution
Substitute u = (x^2 + x^-2)^(1/2). Solution
IBP with u equal to the integrand. Solution
Substitute u = log x; IBP twice. Solution

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1995:

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1996:

Simplify the integrand. Solution
IBP with u equal to the integrand. Solution
IBP with u = x. Solution
Partial fraction decomposition. Solution
Substitute u = sin x; factor u from denominator;
partial-fraction-like decomposition.
Solution
Multiply numerator and denominator by (x-1)^(1/2);
expand; integrate each term.
Solution
Long division. Solution

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1997:

Watch the sign! Solution
IBP with u = x. Solution
Substitute u = sin x. Solution
Integrate each term. Solution
Substitute u = e^x. Solution
Substitute u = log t. Solution
Partial fraction decomposition. Solution
"Rationalize" the denominator. Solution
Multiply numerator and denominator by (1 - sin x);
expand; integrate term by term.
Solution

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1998:

Integrate each term. Solution
Partial fraction decomposition by inspection. Solution
Expand and integrate each term. Solution
Trigonometric substitution. Solution
Substitute u = (x-7)^(1/2). Solution
Complete the square; substitute u=x+1. Solution
Complete the square; substitute u=x+1. Solution
Integrate by parts. Solution
Trigonometric identity. Solution
Substitute x = u^2; trigonometric substitution. Solution
Trigonometric identity. Solution
If you haven't memorized it, try substituting u = cos x. Solution
Substitute u = sin x. Solution
Substitute u = e^x; partial fraction decomposition. Solution
Substitute u = e^x; partial fraction decomposition. Solution

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This page is under construction; the links to solutions do not work yet.


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