Cynthia can wallpaper a room in 4 hours and her brother can do it in 6 hours. How long would it take them if they work together

Mathematics

1 answer:

Debora [2.8K]3 years ago

3 0

Answer:

2 hours and 24 minutes

Step-by-step explanation:

cynthia can wallpaper a room 4 hours with means in 1 hour she can wallpaper 1/4th of the room, her brother can wallpaper the same room in 6 hours so I'm 1 hour he can wallpaper 1/6 of the room.

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$\displaystyle\int\frac{x^2+x-3}{(x^3+x^2-4x-4)^2}\,\mathrm dx$

Notice that $x^3+x^2-4x-4=x^2(x+1)-4(x+1)=(x-2)(x+2)(x+1)$ . Decompose the integrand into partial fractions:

$\dfrac{x^2+x-3}{(x-2)^2(x+2)^2(x+1)^2}$
$=\dfrac1{3(x+1)}-\dfrac{11}{32(x+2)}-\dfrac1{3(x+1)^2}-\dfrac1{16(x+2)^2}+\dfrac1{96(x-2)}+\dfrac1{48(x-2)^2}$

Integrating term-by-term, you get

$\displaystyle\int\frac{x^2+x-3}{(x^3+x^2-4x-4)^2}\,\mathrm dx$
$=-\dfrac1{48(x-2)}+\dfrac1{3(x+1)}+\dfrac1{16(x+2)}+\dfrac1{96}\ln|x-2|+\dfrac13\ln|x+1|-\dfrac{11}{32}\ln|x+2|+C$