1.

If `int(sin^(4)x)/(cos^(8)x)dx=atan^(7)x +btan^(5)x+C` , thenA. 7a = 5bB. 5a = 7bC. 7a + 5b = 0D. 5a + 7b = 0

Answer» Correct Answer - a
We have `I=int(sin^(4)x)/(cos^(8)x)dx`
`rArr I=int(tan^(4)x)/(cos^(4)x)dx` " " `["Dividing" N^(r) and^(r) "by" cos^(4)x]`
`rArr I=inttan^(4)x(1+tan^(2)x)dx (tanx)`
`rArrI=int(tan^(4)x+tan^(6)x)d (tanx)=(tan^(5)x)/(5)+(tan^(7)x)/(7)+C`
`:. a=(1)/(7)and b =(1)/(5)rArr7a=5b`


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