Can someone please help ASAP !!!!!!!!!!

Mathematics

1 answer:

denpristay [2]2 years ago

3 0

Oh girl idek. What grade is this

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A dome of a building is in the form of a hemisphere from inside it was whitewashed at the cost of rupees 4989.60 if the cost of

Luda [366]

Answer: $249.48\ m^2; 369.168\ m^3$

Step-by-step explanation:

Given

Cost of white-washing =Rs. 4989.60

Rate =20 per meter square

So, inside area of = $\dfrac{4989.60}{20}=249.48\ m^2$

The surface area of dome= $4\pi\ r^2=249.48$

$4\times 3.142\times r^2=249.48\\r^2=\frac{249.48}{4\times 3.142}=19.85\\r=4.455\ m$

The volume of air in the dome $V=\frac{4}{3}\pi r^3$

$V=\frac{4}{3}\cdot 3.142\cdot (4.45)^3\\V=369.17\ m^3$

6 0

2 years ago

Find a particular solution to y" - y + y = 2 sin(3x)

leonid [27]

Answer with explanation:

The given differential equation is

y" -y'+y=2 sin 3x------(1)

Let, y'=z

y"=z'

$\frac{dy}{dx}=z\\\\d y=zdx\\\\y=z x$

Substituting the value of , y, y' and y" in equation (1)

z'-z+zx=2 sin 3 x

z'+z(x-1)=2 sin 3 x-----------(1)

This is a type of linear differential equation.

Integrating factor

$=e^{\int (x-1) dx}\\\\=e^{\frac{x^2}{2}-x}$

Multiplying both sides of equation (1) by integrating factor and integrating we get

$\rightarrow z\times e^{\frac{x^2}{2}-x}=\int 2 sin 3 x \times e^{\frac{x^2}{2}-x} dx=I$

$I=\frac{-2\cos 3x e^{\fra{x^2}{2}-x}}{3}+\int\frac{2x\cos 3x e^{\fra{x^2}{2}-x}}{3} dx -\int \frac{2\cos 3x e^{\fra{x^2}{2}-x}}{3} dx\\\\I=\frac{-2\cos 3x e^{\fra{x^2}{2}-x}}{3}+\int\frac{2x\cos 3x e^{\fra{x^2}{2}-x}}{3} dx-\frac{2I}{3}\\\\\frac{5I}{3}=\frac{-2\cos 3x e^{\fra{x^2}{2}-x}}{3}+\int\frac{2x\cos 3x e^{\fra{x^2}{2}-x}}{3} dx\\\\I=\frac{-2\cos 3x e^{\fra{x^2}{2}-x}}{5}+\int\frac{2x\cos 3x e^{\fra{x^2}{2}-x}}{5} dx$