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1x1+3x3+5x5+7x7+9x9
=1+9+25+49+81
=165
2x2+4x4+6x6+8x8
=4+16+36+64
=120
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20 x 1 + 20 x 2 + 20 x 3 + 20 x 4 + 20 x 5 + 20 x 6 = ?
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x ... x 100 = ?
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20x1+20x2+20x3+20x4+20x5+20x6= 20x(1+2+3+4+5+6)= 20 x 21 = 420
Còn câu 2 mik thấy khó quá cho mik xin lỗi nha
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có rút gọn phân số 35/6 về phân số đc ko ? Nếu có thì mn rút gọn cho mik nhé !
Ai xong tr tui k cho
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X = ( 1+10 ) * 10 / 2 = 11 * 10 / 2 = 110 / 2 = 55
X= (2+20) * 10 /2 = 110
X= (1+19)*10/2= 100
1+2+3+4+5+6+7+8+9+10= (10+1)X10 : 2 = 55
2+4+6+8+10+12+14+16+18+20 = (20+2)x10 : 2 = 110
1+3+5+7+9+11+13+15+17+19 = (19+1) x 10 : 2 = 100
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45x6=270
1+1+2+2+3+3+4+4+5+5+6+6+7+7+8+8+9+9
=(1x2)+(2x2)+(3x2)+(4x2)+(5x2)+(6x2)+(7x2)+(8x2)+(9x2)
=2+4+6+8+10+12+14+16+18
=6+6+8+10+12+14+16+18
=12+8+10+12+14+16+18
=20+10+12+14+16+18
=30+12+14+16+18
=42+14+16+18
=56+16+18
=72+18
=90
78:5=15(dư3)
45:5=9
x:5=25
x= 25x5
x= 125
tk nhé
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Đổi x thành a, ta có:
(1 + a) + ( 2 + a) + (3 + a) + ( 4 + a) + (5 + a) = 10 x 5
1 + a + 2 + a + 3 + a + 4 + a + 5 + a = 50
a + a + a + a + a + 1 + 2 + 3 + 4 + 5 = 50
a x 5 + 15 = 50
a x 5 = 50 - 15
a x 5 = 35
a = 35 : 5
a = 7
(1+X)+(2+X)+(3+x)+(4+x)+(5+x)=5 NHAN 10
1+X+3+X+2+X+4+X+5+X=50
X NHAN5+1+2+3+4+5=50
x NHAN 5+15=50
X NHAN5=50-15=35
X=35:5=7
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1 + 1 x 2 = 3
1 + 4 x 5 - 4 + 3 = 20
1 + 1 x 2 = 1 + 2 = 3
1 + 4 x 5 - 4 + 3 = 1 + 20 - 4+ 3 = 20