1.

`lim_(x rarr pi/4)(tan^3x-tanx)/(cos(x+pi/4)`

Answer» Correct Answer - `-4`
Given limit `=lim_(xto(pi)/(4))(tanx(tanx+1)(sinx-cosx))/(cosx.cos(x+(pi)/(4)))`
`=lim_(xto(pi)/(4))(tanx(tanx+1)(sinx-cosx))/(cosx.cos(x+(pi)/(4)))`
`=-lim_(xto(pi)/(4))(tanx(tanx+1)(cosx-sinx))/(cosx. cos(x+(pi)/(4)))`
`=-sqrt2lim_(xto(pi)/(4))(tanx(tanx+1)((1)/(sqrt2)cosx-(1)/(sqrt2)sinx))/(cosx.cos(x+(pi)/(4)))`
`=-sqrt2lim_(xto(pi)/(4))(tanx(tanx+1).cos(x+(pi)/(4)))/(cosx. cos(x+(pi)/(4)))=-sqrt2lim_(xto(pi)/(4))(tanx(tanx+1))/(cosx)`
`=-sqrt2.(1xx(1+1))/(((1)/(sqrt2)))=-4.`


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