1) Daca ab +ac =20 si b+c=5, calculeaza a^3 (b+c)

2) Daca a^2 - ab + ac = -15 si a=5 calculeaza (b-c) ^2

1) a b + a c = 20 si b + c = 5

ab + ac = 20

a ( b + c ) = 20 → am dat factor comun pe a

a × 5 = 20

a = 20 : 5

a = 4

a³ × ( b + c ) = 4³ × 5 = 64 × 5 = 320

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2) a² - ab + ac = - 15 si a = 5

5² - a ( b - c ) = - 15

25 - 5 × ( b - c ) = - 15

5 × ( b - c ) = - 15 - 25 = - 40

b - c = ( - 40) : 5

b - c = - 8

( b - c ) ² = ( - 8 ) ² = 64