Find the function with the given derivative whose graph passes through the point p g'(x)= #1/x^2#+2x ,p(-1,1) HELP ME PLEASE??

3 Answers
Dec 9, 2017

#g(x) = -x^-1+x^2-1#

Explanation:

We have

#int g'(x)dx = g(x) = int (x^-2+2x)dx = -x^-1+x^2+C_0# but

#g(-1) = 1 rArr -(-1)^-1+(-1)^2+C_0 = 1# and then

#C_0 = -1# so the sought function is

#g(x) = -x^-1+x^2-1#

Dec 9, 2017

See below.

Explanation:

If g'(x)=1/x^2+2x, then #g(x)=int(1/x^2+2x) dx#

#int(x^(-2)+2x)dx=-x^(-1)+x^2+c=-1/(x)+x^2+c#

#g(x)=-1/x+x^2+c#

If #g(x)# passes through point P #(-1,1)# then:

#1=-1/(-1)+(-1)^2+c#

#1=1+1+c=>c=-1#

#g(x)=-1/x+x^2-1#

Dec 9, 2017

#g(x)=x^2-1/x-1#

Explanation:

I'll do it without integral usage (in case you need it that way)

Graph #C_g# passes trough #P(-1,1)# so that means #g(-1)=1#

We have #g'(x)=1/x^2+2x# ,

#(g(x))' = (-1/x)' +2*(x^2/2)'#

#(g(x))'=(x^2-1/x)'#
#g,x^2-1/x# continuous and differentiable
and #(g(x))'=(x^2-1/x)'# so there is one #c# #in##RR# for which

#g(x)=x^2-1/x+c#

  • #g(-1)=1# #<=> c+2=1# #<=> c=-1#

Eventually #g(x)=x^2-1/x-1#