Письмо другу на языке как я провёл зимнии каникулы

Hello, my dear pen pal! i want to tell you about how i spent my winter vacation.they were so full of fun and pleasant surprises that i think i will remember them all my life.on the very first day of the holidays, soft and fluffy snow fell out. the next day my friend and i ran to ride a sled and sculpt snowmen.for a whole week i was in the city and had fun with a friend. in the evenings, my parents and i were slowly preparing for the new year and for christmas.on holidays we came to our grandmother and grandfather, they had a gift for me - a real snowboard! my joy was boundless! the same evening my parents said that we all go to the mountains to a winter resort.there i rolled my snowboard. at first i did not get very well, but eventually i was confidently standing on my feet. to be honest, my dad is a professional snowboarder, so he became my personal trainer.after returning from the resort, i managed to have a good rest and prepare for school.by the way, i am seriously thinking about becoming a professional snowboarder - just like my beloved daddy. tell me about how you spent your winter vacation, i will be very interested.i wish you all the best! i'm waiting for an answer, my dear friend!

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

1-x^2=0

x=+-1

y(-1)=-1/(1+1)=-1/2 минимум

y(1)=1/2 максимум

y''=+x^2)*2x-(1-x^2)*2*2x)/(1+x^2)^3)=(6x^3-6x)/(1+x^2)^3

6x^3-6x=0

x^3-x=0

x=-1 x=0 x=1- точки перегиба