64*25+35*25+25
Tính nhanh:
64×25+35×25+25
64*25+35*25+25
=25*(64+35+1)
=25*100
=2500
: Tinh nhanh
. 64*25+35*25+25
64 x 25 +35 x 25 +25
=(64+35+1) x 25
=100 x 25
=2500
64 x 25 + 35 x 25 + 25
= ( 64 + 35 + 1 ) x 25
= 100 x 25
= 2500
64*25+35*25+25
Ai giải hộ với
64 x 25 + 35 x 25 + 25
= ( 64 + 35 + 1 ) x 25
= 100 x 25
= 2500
64*25+35*25+25
=64*25+35*25+25*1
=(64+35+1)*25
=100*25
=2500
1/5+4/10+9/15+25/25+36/30+49/35+64/40+81/45
1/5+4/10+9/15+25/25+36/30+49/35+64/40+81/45
=1/5 + (4/10:2) + (9/15:3)+25/25 + (36/30:6)+ (49/35:7) + (64/40:8) + (81/45:9)
=1/5 + 1/5 + 1/5 + 1 + 1/5 + 1/5 + 1/5 + 1/5
=1/5 x 7 + 1
=12/5
1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/60+81/45
tính nhanh :
1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/40+81/45
cần gấp mn !!!
Ta có: \(\dfrac{1}{5}+\dfrac{4}{10}+\dfrac{9}{15}+\dfrac{16}{20}+\dfrac{25}{25}+\dfrac{36}{30}+\dfrac{49}{35}+\dfrac{64}{40}+\dfrac{81}{45}\)
\(=\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{4}{5}+\dfrac{5}{5}+\dfrac{6}{5}+\dfrac{7}{5}+\dfrac{8}{5}+\dfrac{9}{5}\)
\(=\dfrac{45}{5}=9\)
\(\dfrac{1}{5}+\dfrac{4}{10}+\dfrac{9}{15}+...+\dfrac{81}{45}\\ =\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+...+\dfrac{9}{15}\\ =\dfrac{\left(1+2+3+...+9\right)}{15}=\dfrac{\left(1+9\right)x9:2}{15}\\ =\dfrac{10x9:2}{15}=\dfrac{45}{15}=3\)
1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/40+81/45
1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/40+81/45 = 1/5 + 2/5 + 3/5 + 4/5 + 1 + 6/5 + 7/5 + 8/5 + 9/5 = (1/5 + 9/5) + (2/5 + 8/5) + (3/5 + 7/5) + (4/5 + 6/5) + 1 = 2 + 2 + 2 + 2 + 1 = 9
Tinh nhanh
9/15 cong 16/20 cong 25/25 cong 30/36 cong 49/35 cong 64/40 cong 81/45 cong 100/50
C = 8/9 * 15/16 * 24/25 * 35/36 * 48/49 * 63/64