a. 32 + (–49) – |–15|
b. (–12) – 80 : (–16) + (–25) . (–3)
c. 17 – 15 . (–2)2 – 144 : |–16|
d. Tính hợp lý: –35 . 54 + 32(–63) – 32(–17)
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2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)
\(\text{35 + (–47) – |–12|}\)
\(=-12-12\)
\(=-24\)
\(\text{(–15) – 70 : (–14) + (–32) . (–2)}\)
\(=-15+5+64\)
\(=-10+64\)
\(=54\)
\(\text{ 15 – 12 . (-3)^2 – 135 : |–15|}\)
\(=15-12.9-135:15\)
\(=15-108-9\)
\(=-102\)
Tính hợp lý:
\(\text{ –24 . 78 + 24(–35) – 24(–13)}\)
\(=24.\left(-78+\left(-35\right)-\left(-13\right)\right)\)
\(=24.\left(-100\right)\)
\(=-2400\)
học tốt
a. 32 + (–49) – |–15|
= 32 - 49 - 15
= -32
b. (–12) – 80 : (–16) + (–25) . (–3)
= - 12 + 5 + 75
= 68
c. 17 – 15 . (–2)2 – 144 : |–16|
= 17 - 15.4 - 144 : 16
= 17 - 60 - 9
= -52
a, 32 + (-49) -|-15|
= -17 - 15
= -32
b, (-12) - 80 : (-16) + (-25) . (-3)
= (-12) - (-5) + 75
= -7 + 75
= 68
c, 17 - 15 . (-2)2 - 144 :|-16|
= 17 - 15. 4 - 144 : 16
= 17 - 60 - 9
= -43 - 9
= -52
d, -35 . 54 + 32.(-63) - 32(-17)
= -1890 + 32. [-63 - (-17)]
= -1890 + 32. (-46)
= -1890 + (-1472)
= -3362.
Tham khảo nha!!!