B₈=5/3¹²;b₁₄=5/3⁶;S₁₁=?;
b₈=b₁q⁷;
b₁₄=b₁q¹³;
b₁₄/b₈=q¹³⁻⁷=q⁶;
q=⁶√(5/3¹² :5/3⁶)=⁶√(1/3⁶)=1/3;
b₁=b₈/q⁷=5/3¹² :1/3⁷=5/3¹²⁻⁷=5/3⁵;
S₁₁=b₁(1-q¹¹)/(1-q);
S₁₁=5/3⁵·(1-1/3¹¹)/(1-1/3)=5/3⁵·(3¹¹-1)/3¹¹ :(2/3)=
=5·(3¹¹-1)·3/3⁵·3¹¹·2=5·(3¹¹-1)·3¹⁻⁵⁻¹¹·2⁻¹=5·(3¹¹-1)·3⁻¹⁵2⁻¹;
1.
<span> 3x-3y+x²y-xy²=3(x-y)+xy(x-y) = (3+xy)(x-y)
2.
7(x+8)+(x+8)(x-8) = (x+8)(7+x-8)
3.
(x+5)4x-(2x+5)² = (4x²+20x)-</span>(4x²+20x+25) = -25 = (-5)*5<span />
<span>D) – 0,2
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∫sin(3x+π/6)dx обозначим 3х+π/6 = t 3dx=dt dx=dt/3
∫sint*dt/3=-1/3*cost+c=-1/3cos(3x+π/6)+c