Tính nhanh:
a) -3 + 8 + (-13) + 18 + ...+ (-53) + 58
b) -40 + (-39) + ... + 33+ 34 + 35
Tính theo cách hợp lý:
a) (-3) + 8 + (-13) + 18 + ... + (-53) + 58
b) (-40) + (-39) + ... + 33 + 34 + 35
a) ( -3 ) + ( 8 ) + ( -13 ) + 18 + ... + ( -53 ) + 58
= [ ( -3 ) + 8 ] + [ ( -13 ) + 18 ] + ... + [ ( -53 ) + 58 ] có 6 cặp
= 5 + 5 + ... + 5
= 5 x 6
= 30
b) ( -40 ) + ( -39 ) + ... + 33 + 34 + 35
= [ ( -35 ) + 35 ] + [ ( -34 ) + 34 ] + ... + [ ( -1 ) + 1 ] + 0 + ( -40 ) + ( -39 ) + ... + ( -36 )
= 0 + 0 + ... + 0 + 0 + ( -190 )
= -190
Tinh theo cách hợp lý
a) -3 + 8 + (-13) + 18 +...+ (-53) + 58
b) (-40) + (-39) +...+ 33 + 34 + 35
Tính theo cách hợp lý:
a) (-3) + 8 + (-13) + 18 + ... + (-53) + 58
b) (-40) + (-39) + ... + 33 + 34 + 35
a)=((-3)+8)=((-13)+18)+...+((-53)+58)
=5+5+...+5
=30
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50+51+52+53+54+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=?
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50.
Có ai rảnh đâu mà đi ngồi cộng ngần đấy số ra.
11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40
11 + 12 + 13 + ... + 40
số số hạng : ( 40 - 11 ) : 1 + 1 = 30
tổng : ( 40 + 11 ) x 30 : 2 = 765
đáp số : 765
bn ơi kết quả là 765 bn nhé!!
đúng 100%
chúc bn học tốt nhé
tính 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50-999-888-777-666-555-444-333-222-111
nhanh nhé
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31
+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+4
7+48+49+50-999-888-777-666-555-444-333-222-111= -3720