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2d
answered Having trouble solving a problem involving hyperbolic trignometric functions
2d
answered Find the parameter a of function $y = 2\sin(\frac{\pi}{4}x+a)$
2d
answered trying to solve $\sqrt{\cos(x)-2\cos(2x)}+\sqrt{2}\cos(2x)=0$
2d
answered What function is this? $\sum_{k=0}^\infty \frac{2^{2k}z^{2k-1}}{(2k)!}$
2d
comment Find period of $y=\sin\frac1x$
@DDK, If $$f(x)=\sin\dfrac1x,f(x+2n\pi)=\sin\dfrac1{x+2n\pi}\ne\sin\dfrac1x$$ in general
2d
comment Find period of $y=\sin\frac1x$
See math.stackexchange.com/questions/949291/…
2d
answered Trigonometric equation $\sin v = -1/\sqrt{2}$
2d
comment Solve this integral:$\int_0^\infty\dfrac{\arctan x}{x(x^2+1)}\mathrm dx$
Using $\int_a^bf(x)\ dx=\int_a^bf(a+b-x)\ dx$ $\displaystyle\int_0^{\frac{\pi}{2}}\dfrac{x}{\tan x}=\int_0^{\frac{\pi}{2}}x\tan x\ dx$ $\int x\tan x\ dx=x\int\tan x\ dx-\int\left(\dfrac{dx}{dx}\int\tan x\ dx\right)dx$ $=x\int\tan x\ dx-\int\left(\ln\sec x\right)dx$ $=x\int\tan x\ dx+\int\left(\ln\cos x\right)dx$ See math.stackexchange.com/questions/37829/…
2d
comment Trying to solve $\sqrt{7-4\sqrt2 \sin x}=2\cos(x)-\sqrt2 \tan(x)$
@CopperKettle, As we need $$2\cos x-\sqrt2\tan x=\dfrac{2-2\sin^2x-\sqrt2\sin x}{\cos x}=-\sqrt2\cdot\dfrac{\sqrt2\sin^2x+\sin x-\sqrt2}{\cos x}\ge0$$
2d
answered How do i evaluate $ \bigtriangleup^{10}(1-ax)(1-bx^{2})(1-cx^{3})(1-dx^{4}) $
2d
comment Trying to solve $\sqrt{7-4\sqrt2 \sin x}=2\cos(x)-\sqrt2 \tan(x)$
@CopperKettle, $$2\cos x-\sqrt2\tan x=\dfrac{2\cos^2x-\sqrt2\sin x}{\cos x}$$ Now $$\cos^2x=1-\sin^2x$$
2d
comment $z=100^2-x^2$. Then, how many values of $x,z$ are divisible by $6$?
Let us continue this discussion in chat.
2d
comment $z=100^2-x^2$. Then, how many values of $x,z$ are divisible by $6$?
@justintakro, $$x=0\implies100\pm x=100$$ If $x=3k,$ none is divisible by $3$. If $$x=3k+1,100+x=101+3x\equiv1\pmod3\not\equiv0$$ If $$x=3k+2,100+x=102+3x=3(x+34)\equiv0\pmod3$$
2d
comment $z=100^2-x^2$. Then, how many values of $x,z$ are divisible by $6$?
@justintakro, parity means even or odd. What's ur confusion?
2d
comment $z=100^2-x^2$. Then, how many values of $x,z$ are divisible by $6$?
@Jack, $a|b$ means $a$ divides $b$ Sorry for the confusion
2d
answered Trying to solve $\sqrt{7-4\sqrt2 \sin x}=2\cos(x)-\sqrt2 \tan(x)$
2d
comment Verification of an indefinite integral with trigonometric functions
See math.stackexchange.com/questions/1412207/…
2d
comment how to solve 192-2a^2-a=m(6a+1)?
@Alberico, $6a+1<6\cdot41+1$ So, $6a+1$ can be $7,13,19,7\cdot13 ,7\cdot19$
Aug
28
comment Proving that $a^{b}$ is rational (Elementary number theorey)
See math.stackexchange.com/questions/104119/… and cut-the-knot.org/do_you_know/irrat.shtml
Aug
28
answered Integration of the square root of a quadratic