User Zaz

3

7

votes

2

answers

3k

views

When do permutations commute?

abstract-algebra permutations

Nov 12 at 20:29 Changming Sun 101

3

7

votes

2

answers

2k

views

Why don't we use the partial derivative symbol for normal derivatives?

notation partial-derivative

Feb 26 '19 at 0:45 user541686 11.2k

3

5

votes

4

answers

20k

views

How much faster is the Trachtenberg system?

arithmetic

Aug 2 '19 at 14:20 Ray Penber 113

1

5

votes

1

answer

154

views

How can I mentally calculate $\cos(x), x∈(0.7, 1.2)$

trigonometry mental-arithmetic

Nov 17 '18 at 16:33 Zaz 996

4

votes

5

answers

3k

views

Work out the values of a and b from the identity $x^2 - ax + 144 = (x-b)^2$

algebra-precalculus polynomials

Apr 24 '12 at 16:40 Community♦ 1

1

3

votes

2

answers

5k

views

Calculate area of triangle in space given points

vectors area

Oct 9 '19 at 15:00 Community♦ 1

3

votes

1

answer

104

views

Is this a correct way to prove by induction?

proof-verification induction

Sep 29 '17 at 20:59 Stu 1,620

3

votes

1

answer

101

views

Is writing equalities within an equation abuse of notation?

notation boolean-algebra

Sep 15 '17 at 18:01 Epiousios 2,840

3

votes

3

answers

184

views

Why doesn't $\int_{-1}^{1}\frac{dx}{x} = \ln|x|\biggr\rvert_{-1}^{1} = 0$?

integration limits definite-integrals area

Feb 3 '16 at 19:51 Mhenni Benghorbal 45.2k

1

3

votes

1

answer

4k

views

How can I see alternative trigonometry solutions on a calculator?

trigonometry calculator

Jun 8 '11 at 12:01 Zaz 996

2

votes

1

answer

4k

views

Using the Uniform Distribution of Deaths assumption

actuarial-science

Aug 14 '18 at 3:01 Community♦ 1

2

votes

2

answers

235

views

Prove a map X → X must be bijective

proof-writing permutations

Sep 11 '17 at 14:55 miracle173 8,651

1

vote

2

answers

83

views

Visual proof that $\mathbb Z_m × \mathbb Z_n = \mathbb Z_{mn} \iff \gcd(m,n) = 1$

visualization

Oct 20 '17 at 16:27 Community♦ 1

1

vote

1

answer

28

views

Are there multiple ways to translate a permutation $\alpha$ to a permutation $\beta$?

permutations

Sep 16 '17 at 17:00 kimchi lover 20.8k

1

vote

1

answer

64

views

Why do we always use phase lag instead of phase gain?

ordinary-differential-equations

Jul 9 '17 at 0:30 Community♦ 1

1

vote

2

answers

65

views

Evaluating the integral $\int{\frac{x^2-2x-1}{(x-1)^2(x^2+1)}}$

integration indefinite-integrals

Jan 29 '16 at 16:02 Zaz 996

0

votes

1

answer

1k

views

Calculating error on slope of graph

statistics regression data-analysis linear-regression slope

Oct 21 at 7:01 Community♦ 1

0

votes

1

answer

123

views

Formula for CDF of investment returns

probability probability-distributions finance

Apr 6 '19 at 18:41 Zaz 996

0

votes

1

answer

95

views

Is this a standard way to prove by induction?

proof-writing induction

Sep 29 '17 at 22:46 BDN 512

0

votes

2

answers

139

views

Locally constant function vs step function

functions

Aug 18 '16 at 7:35 Zaz 996

0

votes

1

answer

117

views

“Compute $dy$ as $x$ changes from $2$ to $2.1$”?

calculus

Oct 24 '15 at 20:12 Emilio Novati 57.8k

-3

votes

4

answers

126

views

How to calculate $\sum_{k=1}^∞{\frac{1}{k(k+1)}}$ [duplicate]

sequences-and-series

Mar 5 '16 at 21:33 Mark Viola 155k

2

-3

votes

1

answer

134

views

How to approach this integration problem? [closed]

calculus integration

Feb 16 '16 at 22:26 3SAT 7,342

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23 Questions

When do permutations commute?

Why don't we use the partial derivative symbol for normal derivatives?

How much faster is the Trachtenberg system?

How can I mentally calculate $\cos(x), x∈(0.7, 1.2)$

Work out the values of a and b from the identity $x^2 - ax + 144 = (x-b)^2$

Calculate area of triangle in space given points

Is this a correct way to prove by induction?

Is writing equalities within an equation abuse of notation?

Why doesn't $\int_{-1}^{1}\frac{dx}{x} = \ln|x|\biggr\rvert_{-1}^{1} = 0$?

How can I see alternative trigonometry solutions on a calculator?

Using the Uniform Distribution of Deaths assumption

Prove a map X → X must be bijective

Visual proof that $\mathbb Z_m × \mathbb Z_n = \mathbb Z_{mn} \iff \gcd(m,n) = 1$

Are there multiple ways to translate a permutation $\alpha$ to a permutation $\beta$?

Why do we always use phase lag instead of phase gain?

Evaluating the integral $\int{\frac{x^2-2x-1}{(x-1)^2(x^2+1)}}$

Calculating error on slope of graph

Formula for CDF of investment returns

Is this a standard way to prove by induction?

Locally constant function vs step function

“Compute $dy$ as $x$ changes from $2$ to $2.1$”?

How to calculate $\sum_{k=1}^∞{\frac{1}{k(k+1)}}$ [duplicate]

How to approach this integration problem? [closed]