A) 10a^2 - 6ab + b^2;
b) 9b^2 - a^2 +6ab - 9b^2 = 6ab - a^2;
c) 25a^2+70ab +49b^2 - 70ab = 25a^2 + 49b^2;
d) 64a^2 - 16ab +b^2 - 64a^2 = b^2 - 16ab
0.6x^2 + 0.8x - 7.8 = 0 / * 10
6x^2 + 8x - 78 = 0
D = 64 + 4*6*78 = 1936 = 44^2
x1 = ( - 8 + 44)/12 = 36/12 = 3
x2 = ( - 8 - 44)/12 = - 52/12 = - 13/3
Х-начальное число
х*0,85
0,85х*1,1=0,935х
х-0,935=13
0,065х=13
х=13:0,065
х=200
200=200
25x -1/x=0
25x²-1=0 x≠0
25x²=1
x²=1/25
x=1/5 x=-1/5
(0;9)
(3;0)
3х+4у=10. *10
10х-3у=17 *-3
40у+9у=100+(-51)
49у=49
У=1
3х+4*1=10
3х=10-4
3х=6
Х=2