1) Calculer les expressions suivantes en utilisant le calcul astucieux : = A = -0,4 x 10 (-4,2) × (-2,5) x 3 B = 8X (-1) X (-1,25) x6,07 x (-0,2) × (-5)

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A = -0,4×10(-4,2)×(-2,5)×3

A = -(0,4×10×4,2×2,5×3

A = -(4×4,2×2,5×3)

A = -(10×4,2×3)

A = -(42×3)

A = -126

B = 8×(-1)×(-1,25)×6,07×(-0,2)×(-5)

B = 8×1×1,25×6,07×0,2×5

B = 10×6,07×0,2×5

B = 2×6,07×5

B = 10×6,07

B = 60,7

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