4х во 2 степени +20х -(4х во2 +20х +25)
4х во 2 +20х -4х во 2 -20х -25
-25
По формуле: sin(15-45)=sin(-30)=-0,5
1) b1=25, b2=-5
q=b2/b1=-5/25=-1/5=-0.2
S=b1/(1-q)=25/(1+0.2)=25/1.2=20ц 5/6
2) S=124, b1=31
S=b1/(1-q)
1-q=b1/S
q=1-(b1/S)=1-(31/124)=1-(1/4)=3/4
3) b1 = (-1) * 12/4 = -3
b2 = 1* 12/8 = 1.5
q=b2/b1=1.5/-3=-0.5
S=b1/(1-q)=-3/(1+0.5)=-3/1.5=-2