20a(b-a)+5(2a-b²)=20ab-20a²+10a-5b²=
1)20×(-0,35)×3= -7×3= -21
2)-20×(-0,35)²= -20×0,1225= -2,45
3) 10×(-0,35)= -3,5
4)-5×(3)²= -5×9= -81
-21-2,45-3,5-81= -107,97
X²/(x²+1)=z
(1+a)z²-3az+4a=0
D=9a²-16a(1+a)=9a²-16a-16a²=-7a²-16a
D≥0, -7a²-16a≥0
7a²+16a≤0
a(7a+16)≤0
1)a≥0 ∧ 7a+16≤0, a≥0 ∧ a≤-16/7 , a∈∅
2)a≤0 ∧ 7a+16≥0, a≤0 ∧ a≥-16/7, a∈/-16/7,0/
Otvet (-1/2,0/ pravilnyj...........
3-1,2=1,8
5-1,3=3,7
6-1,3=4,7
<span>a) (5+x)</span>² = 25 +10x + x²<span>
б) (1-3x)</span>² = 1 - 6x + 9x²<span>
в) (3a-10b)</span>² = 9a² -60ab + 100b²<span>
г) (x</span>²<span> +4)</span>² = x⁴ + 8x² + 16<span>
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