<span>4x^2-5x-6=0
D = 25 + 4*4*6 = 121
x1 = (5 - 11)/8 = -6/8 = -3/4
x2 = (5+11)/8 = 16/8 = 2
</span><span>2)-3x^2=x
-3x^2 - x = 0
3x^2 + x = 0
x(3x + 1) = 0
x = 0; x = -1/3
</span>
10) -(b - 2)(b +2) - 2(b+4)(b +2) = -b² + 4 -2(b² + 6b + 8) = -b² +4 -2b² -12b -16=
= -3b² -12b -12
11) = a² -2a -3 - a³ - 18a² - 108a - 216 = -a³ -17a² -110a - 219
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ВС=а;АС=в;АВ=с;<В=180-(30+45)=105°;по теореме синусов:sin105 / 8 =sin30 / b =sin45 / c; b=8sin30/sin105 = 4/sin105; c=4√2/sin105=√2 ·b; b=4/ sin(90+15)=4/cos15≈4/0,9613≈4,16 cм ; c=4,16·√2≈5,88 см