800-(800*0.7)=240р стоит 1 свитер со скидкой
800+240=1040р за 2 свитера
Y`=-9/x²+1=(-9+x²)/x²=0
x²=9
x=-3 U x=3
+ _ +
--------------(-3)-------------------(3)-----------------------
min
ymin=y(3)=3+3+11=17
3x(2x-1)=0
x1=0
x2=1/2
x²=1/25
x1=1/5
x2=-1/5
4x²-7x-2=0
D=49-4*4*2=49-32=17
x1=7+√17/8
x2=7-√17/8
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