а) <span>-2/9+5/18=0,005 и <span>3,9-4,7=-0,8 б) <span>-22/7*1=-3,14 и <span>3/11 =0,27 и <span>-5,6*(-1,2)= 6,72 в)<span> -7,5:(-0,25)=30 и <span>-0,8:(-0,6)=1,33</span></span></span></span></span></span></span>
(x+2)²+(x-3)²=13
x²+4x+4+x²-6x+9=13
2x²-2x=0
2x(x-1)=0
x=0 x=1