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125 -85+80 = 120 ; 21 nhan 2 nhan 4 = 168 ; 68 + 32 -10 = 90 ; 147 : 7 nhan 6 = 126 ; 375 - 10 nhan 3 = 345 ; 64 :8 + 30 = 38
Tính giá trị biểu thức:
125 - 85 + 80
21 x 2 x 4
68 + 32 - 10
147 : 7 x 6
375 - 10 x 3
64 : 8 + 30
\(\text{a,}4+8+12+...+80=\frac{\left(80+4\right).20}{2}=840\)
\(b,80-76+72-68+...+8-4=\left(80+72+64+...+8\right)-\left(76+68+60+4\right)\)
\(=\frac{\left(80+8\right).10}{2}-\frac{\left(76+4\right).10}{2}\)
\(40\)
Câu c tương tự câu b
1 + 10 + 100 + 500 + 2000 + 300 - 50 + 60 - 70 + 80 = 2931 nha bạn
650 x 34 + 34 x 2 x 135 + 34 x 80
= 650 x 34 + 34 x 270 + 34 x 80
= 34 x ( 650 + 270 + 80 )
= 34 x 1000
= 34000
Tick nha
650 x 34 + 34 x 2 x 135 + 34 x 80
= 650 x 34 + 34 x 270 + 34 x 80
= 34 x ( 650 + 270 + 80 )
= 34 x 1000
= 34000
x + 200 = 500 - 80
x + 200 = 420
x = 420 - 200
x = 220
ai k mik mik k lại
x+200=500-80
x+200=420
x=420-200
x=220
1.
a) \(125+80+375+220\)
\(=\left(125+375\right)+\left(80+220\right)\)
\(=500+300\)
\(=800\)
b) \(25.11.8.4.125\)
\(=\left(25.4\right).\left(8.125\right).11\)
\(=100.1000.11\)
\(=1100000\)
c) \(18.74+18.27-18\)
\(=18.\left(74+27-1\right)\)
\(=18.100\)
\(=1800\)
d) \(75.23+75.77-500\)
\(=75.\left(23+77\right)-500\)
\(=75.100-500\)
\(=7500-500\)
\(=7000\)
e) \(150:\left[25.\left(18-4^2\right)\right]\)
\(=150:\left[25.\left(18-16\right)\right]\)
\(=150:\left[25.2\right]\)
\(=150:50\)
\(=3\)
f) \(125.23.2.8.50\)
\(=\left(125.8\right).\left(2.50\right).23\)
\(=1000.100.23\)
\(=2300000\)
g) \(235+88+165+12\)
\(=\left(235+165\right)+\left(88+12\right)\)
\(=400+100\)
\(=500\)
h) \(71.32+71.68-1100\)
\(=71.\left(32+68\right)-1100\)
\(=71.100-1100\)
\(=7100-1100\)
\(=6000\)
i) \(6^7:6^6+4^3.2-24^0\)
\(=6+64.2-1\)
\(=6+128-1\)
\(=133\)
j) \(546-6.\left[158:\left(30+7^2\right)\right]\)
\(=546-6.\left[158:\left(30+49\right)\right]\)
\(=546-6.\left[158:79\right]\)
\(=546-6.2\)
\(=546-12\)
\(=534\)
k) \(268+147+132+253\)
\(=\left(268+132\right)+\left(147+253\right)\)
\(=400+400\)
\(=800\)
2.
a) \(7x=707\)
\(x=707:7\)
\(x=101\)
b) \(6x+5=47\)
\(6x=47-5\)
\(6x=42\)
\(x=42:6\)
\(x=7\)
c) \(35:\left(x+1\right)=7\)
\(x+1=35:7\)
\(x+1=5\)
\(x=5-1\)
\(x=4\)
d) \(12+\left(29-3x\right)=35\)
\(29-3x=35-12\)
\(29-3x=23\)
\(3x=29-23\)
\(3x=6\)
\(x=6:3\)
\(x=2\)
e) \(2.4^x+10^1=138\)
\(2.4^x=138-10\)
\(2.4^x=128\)
\(4^x=128:2\)
\(4^x=64=4^3\)
\(\Rightarrow x=3\)
f) \(7x=140\)
\(x=140:7\)
\(x=20\)
g) \(7\left(15-x\right)+14=84\)
\(7\left(15-x\right)=84-14\)
\(7\left(15-x\right)=70\)
\(15-x=70:7\)
\(15-x=10\)
\(x=15-10\)
\(x=5\)
h) \(3^x.5-15=390\)
\(3^x.5=390+15\)
\(3^x.5=405\)
\(3^x=405:5\)
\(3^x=81=3^4\)
\(\Rightarrow x=4\)
\(120\)\(+\)\(80\)\(=\)\(500\)\(-\)\(x\) \(100\)\(+\)\(100\)\(=\)\(400\)\(-\)\(x\)
\(200\) \(=\)\(500\)\(-\)\(x\) \(200\) \(=\)\(400\)\(-\)\(x\)
\(500\)\(-\)\(200\)\(=\)\(x\) \(400\)\(-\)\(200\)\(=\) \(x\)
\(300\) \(=\) \(x\) \(200\) \(=\) \(x\)
Bạn ơi thiếu kết quả mong bạn xem lại nhé :))