<span>x²-1=2(x²-6x+9) -x² </span>
<span>x²-1-2x²+12x-18+x²=0 </span>
<span>12x-19=0 </span>
<span>12x=19 </span>
<span>x=19/12</span>
<span>
</span>
№938 (3)
81,5 + 4,2 * 10,1^2 = 81,5 + 4,2 * 102,01 = 81,5 + 428,442 = 509,942
№939 (1, 2)
1) 2,4 * 1/4 + 0,5 : 4/5 = 2,4 * 0,25 + 0,5 : 0,8 = 0,6 + 0,625 = 1,225
2) <u>18,9 + 5,58</u> = <u>24,48</u> = 3,4
48 * 0,15 7,2
№940
3/7 ; 0,48 ; 1 ; 18/7 ; 3,032 ; 4 5/9
1) 4 + 2i - 3 - 2i = 1
2) 5 - 4i - 6 - 2i = -1 - 6i
3) -6 + 9i - 10i + 15i² = -6 - i - 15 = -21 - i
4) 9 - 4i² = 9 + 4 = 13
5) 4 - 28i + 49i² = 4 - 28i - 49 = -45 - 28i
6) (2-i)(1-2i)/(5*(1-4i²)) = (2-i-4i+2i²)/(5*5) = -5i/25 = -i/5