Решение смотри во вложении...
<span>1) (0,1-х)(х+0,1)=-(x-0.1)(x+0.1)=-(x²-0.01)=0.01-x²
2)</span><span> (1,2-а)(1,2+а)</span>=1.44-a²
3) <span> (1/3-m)(1/2m-3)</span>=-1/2m²+1/6m+3m-1=-1/2m²+19/6m-1=-1/6(3m²-19m+6)
У=√х+1: 1; 1/2+1=3/2; 2; 3/2 + 1=5/2; 3; 5/2+1=7/2; 4; 5; 11/2;
у=√х-1: -1; -1/2; 0; 1/2; 1; 3/2; 2; 3; 7/2.
А₃= 7
а₉ = -18
а₁=?
d=?
Решение
а₃ = а₁ +2d 7 = а₁ +2d
a₉ = a₁ + 8d, -18 = а₁ +8d вычтем из 2-го уравнения 1-е
получим: -25 = 6d, ⇒ d = -25/6
7 = а₁ +2d = а₁ +2* (-25/6) = а₁ - 25/3
7 = а₁ - 25/3
а₁ = 7 +25/3 = 46/3 = 15 1/3