Verified answer

Ответ:

a) A = -36, [tex]B=\dfrac{2}{9}[/tex]

b) A·B + 4 = -4

Пошаговое объяснение:

a) A = -1-2-3-4-5-6-7-8 = -(1+2+3+4+5+6+7+8) = -((1+8)+(2+7)+(3+6)+(4+5)) =

= -(9+9+9+9) = -4·9 = -36.

[tex]\displaystyle B=\left (-\frac{1}{2} \right ) \cdot \left (-\frac{2}{3} \right ) \cdot \left (-\frac{3}{4} \right ) \cdot \left (-\frac{8}{9} \right ) = \frac{1 \cdot 2 \cdot 3 \cdot 8}{2 \cdot 3 \cdot 4 \cdot 9} = \frac{2 \cdot 3 \cdot 4 \cdot 2}{2 \cdot 3 \cdot 4 \cdot 9} = \frac{2}{9}.[/tex]

[tex]\displaystyle \tt b) \; \tt A \cdot B+4 = -36 \cdot \frac{2}{9}+4 = \frac{-36 \cdot 2}{9}+4 =\frac{-4 \cdot 9 \cdot 2}{9}+4 =-4 \cdot 2+4 = -8+4 = -4.[/tex]

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