F.5 Maths

36.
let f(x)=2x3+x2-1
put x=-2,f(x)=-13
put x=-1,f(x)=-2
put x=0,f(x)=-1
put x=1,f(x)=1
put x=2,f(x)=2
put x=3,f(x)=62
Since f(x)<0 when x=0 and f(x)>0 when x=1
So,the x intercept of the graph y=f(x) is between 0<x<1
Ans:C

13.
let a= k(b^2)/c
the new value of a=k(1.5b)^2/(0.5c)=4.5(k(b^2)/c)
percentage increase of a=(4.5-1)/1X100%=350%
Ans:E
17 it thint the sum should be 3^(n+1)-3
sum of first 9 term=59046
sum of first 8 trem=19680
the 9th term=59046-19680=39366
Ans:B