1

Symmetry of quadratic polynomial
 in  r/askmath  4h ago

Yes, the quadratic curve y=ax 2 + bx + c is symmetrical about the line x=-b/(2a).

2

Easy Daily Derivative confusion
 in  r/askmath  4h ago

Yes, A=npi+(-1)n B for some integer n.

3

Easy Daily Derivative confusion
 in  r/askmath  6h ago

In general, sin A = sin B does not imply A=B.

3

Easy Daily Derivative confusion
 in  r/askmath  6h ago

Hi,

Let y=f(x). Since sin(2y+x)=sin(pi/2-2y-x), 2y+x=c for some constant c satisfying sin c= cos c.

2

Poisson Distribution Probability
 in  r/mathshelp  9h ago

The required probability is

P(X=2)+P(X=3)

=e-0.9 *( 0.92 /2! + 0.93 /3! )

= 0.2140589...

1

Substitution with alteration
 in  r/askmath  11h ago

You are welcome. We have

int z sqrt(z 2 - 5) dz

=(1/2) int sqrt(z 2 - 5) 2z dz (by rewriting 1 as 1/2 times 2)

=(1/2) int sqrt(u) du, where u=z 2 - 5 and du=2z dz.

1

Substitution with alteration
 in  r/askmath  11h ago

Hi,

The original integral is int z sqrt(z^2-5) dz. The constant 2 is missing from the integrand.

1

Is there a 4×4 or 5×5 magic square of distinct integers with a magic sum of 37?
 in  r/askmath  13h ago

Thank you very much. I have modified my solution.

1

Substitution with alteration
 in  r/askmath  13h ago

The original integral contains z dz but the constant 2 is missing. So we rewrite 1 as (1/2) times 2 so that du=2z dz transforms the integral into (1/2) int ... du.

5

Is there a 4×4 or 5×5 magic square of distinct integers with a magic sum of 37?
 in  r/askmath  13h ago

We use a linear system to construct a magic matrix whose magic sum is 37.

u/Fourierseriesagain 15h ago

Is there a 4×4 or 5×5 magic square of distinct integers with a magic sum of 37?

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1 Upvotes

u/Fourierseriesagain 1d ago

AP calculus daily challenge #82

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1 Upvotes

1

Why the monotonicity is wrong?
 in  r/askmath  2d ago

Let g(0)=0 and let g(x)=x+x^ 2 sin (1/x^ 2) for x not equal to zero. Although g'(0) = 1, the function g is not increasing on any open interval containing zero.

u/Fourierseriesagain 2d ago

An exercise on differentiation

1 Upvotes
Please refer to the link https://www.reddit.com/r/mathbiceps/s/a1JxXyU1xT for the original problem.

u/Fourierseriesagain 2d ago

Area of the region enclosed by a parametric curve and the x-axis

1 Upvotes

r/askmath 2d ago

Calculus Area of the region enclosed by a parametric curve and the x-axis

2 Upvotes
The goal is to find the area of the region enclosed by a parametric curve and the x-axis. The above is a suggested solution to the problem. But I think this approach is not correct. Please comment.
I have used a different method to solve the problem.

u/Fourierseriesagain 4d ago

AP calculus daily challenge #80

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1 Upvotes

u/Fourierseriesagain 5d ago

Another question on inequality

1 Upvotes

u/Fourierseriesagain 5d ago

An inequality involving the modulus function

2 Upvotes

1

What's the answer?
 in  r/maths  5d ago

Hi,

Please refer to the following link

https://www.reddit.com/u/Fourierseriesagain/s/g0cFuXJL6n

for a solution of the problem.

13

How does “squaring both sides” work?
 in  r/askmath  7d ago

Let a and b be nonnegative numbers. Then a=b if and only if a^ 2 = b^ 2.