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find-the-area-between-the-curve-y-3-2x-x-2-the-x-axis-and-the-line-y-3-find-the-volume-of-the-solid-generated-when-the-curve-is-rotated-completely-about-the-line-y-3-




Question Number 136076 by physicstutes last updated on 18/Mar/21
find the area between the curve y = 3 + 2x −x^2 , the x−axis  and the line y = 3.   find the volume of the solid generated when the curve is  rotated completely about the line y = 3
findtheareabetweenthecurvey=3+2xx2,thexaxisandtheliney=3.findthevolumeofthesolidgeneratedwhenthecurveisrotatedcompletelyabouttheliney=3
Answered by mr W last updated on 18/Mar/21
Area A=(2/3)×(4×4−2×1)=((28)/3)
AreaA=23×(4×42×1)=283
Commented by mr W last updated on 18/Mar/21
Commented by mr W last updated on 18/Mar/21
volume V  x^2 −2x−3+y=0  (x_2 −x_1 )^2 =(x_2 +x_1 )^2 −4x_1 x_2                       =2^2 −4(−3+y)=4(4−y)  x_2 −x_1 =2(√(4−y))  dV=2π(3−y)(x_2 −x_1 )dy  V=∫_0 ^3 2π(3−y)(x_2 −x_1 )dy    =4π∫_0 ^3 (3−y)(√(4−y))dy    =4π∫_3 ^0 (3−y)(√(1+3−y))d(3−y)    =4π∫_0 ^3 u(√(1+u))du    =4π×(2/(15))[(u+1)^(3/2) (3u−2)]_0 ^3     =4π×((2×58)/(15))    =((464π)/(15))
volumeVx22x3+y=0(x2x1)2=(x2+x1)24x1x2=224(3+y)=4(4y)x2x1=24ydV=2π(3y)(x2x1)dyV=032π(3y)(x2x1)dy=4π03(3y)4ydy=4π30(3y)1+3yd(3y)=4π03u1+udu=4π×215[(u+1)32(3u2)]03=4π×2×5815=464π15

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