52 Вычислите: a) 2,4⋅7,4 – 1,7⋅5,6 – 4,3⋅3,1 + 5,3⋅2,8; б) -12,42 : 4,6 – 31,93 : 3,1 + 1,98 : 2,64 + в) 0,37⋅4,5 - 4,5: (-0,22) + 0,93⋅ (-3,5).

52

a) \(2.4 \cdot 7.4 - 1.7 \cdot 5.6 - 4.3 \cdot 3.1 + 5.3 \cdot 2.8\)

• \(2.4 \cdot 7.4 = 17.76\)
• \(1.7 \cdot 5.6 = 9.52\)
• \(4.3 \cdot 3.1 = 13.33\)
• \(5.3 \cdot 2.8 = 14.84\)

\[17.76 - 9.52 - 13.33 + 14.84 = 8.24 - 13.33 + 14.84 = -5.09 + 14.84 = 9.75\]

б) \(-12.42 : 4.6 - 31.93 : 3.1 + 1.98 : 2.64\)

• \(-12.42 : 4.6 = -2.7\)
• \(-31.93 : 3.1 = -10.3\)
• \(1.98 : 2.64 = 0.75\)

\[-2.7 - 10.3 + 0.75 = -13 + 0.75 = -12.25\]

в) \(0.37 \cdot 4.5 - 4.5 : (-0.22) + 0.93 \cdot (-3.5)\)

• \(0.37 \cdot 4.5 = 1.665\)
• \(4.5 : (-0.22) = -20.4545\)
• \(0.93 \cdot (-3.5) = -3.255\)

\[1.665 - (-20.4545) + (-3.255) = 1.665 + 20.4545 - 3.255 = 22.1195 - 3.255 = 18.8645\]

Ответ: a) 9.75; б) -12.25; в) 18.8645