2.125.18+36.252+4.233.9
dau cham la dau nhan nha cac ban
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3.25.8+4.37.6+2.38.12
=24.25+24.37+24.38
=24.(25+37+38)
=24.100
=2400
chúc bạn học tốt :)!
3.25.8+4.37.6+2.38.12
=24.25+24.37+24.38
=24.(25+37+38)
=24.100=2400
mik nha
a, ( x - 35) . 16 =0
x - 35 = 0 : 16=0
x = 0 + 35
x = 35
b,19. (x - 7) = 19
x - 7=19 : 19=1
x =1 + 7
x =8
c,37.x + 63.x = 200
(37 + 63)x = 200
100.x=200
x =200 : 100
x = 2
19 . ( x - 7 ) = 19
x - 7 = 19 : 19
x - 7 = 1
x = 1+ 7
x = 8
\(\frac{7.9+14.27+21.36}{21.27+42.81+63.108}=\frac{7.3^2+2.7.3^3+3.7.2^2.3^2}{3.7.3^3+2.3.7.3^4+7.3^2.2^2.3^3}=\frac{7.3^2+2.7.3^3+3^3.7.2^2}{3^4.7+2.7.3^5+2^2.7.3^5}\)\(=\frac{7.3^2\left(1+2.3+2^2.3\right)}{3^4.7\left(1+2.3+2^2.3\right)}=\frac{7.3^2}{3^4.7}=\frac{1}{3^2}=\frac{1}{9}\)
Ta có : 28.34 + 68.86
<=> 28.34 + 2.34.86
<=> 28.34 + 172.34
<=> 34.(28+172)
<=> 34.200 = 6800
Ta có : \(\frac{-32}{27}-\left(3x-\frac{7}{9}\right)^3=\) \(\frac{-24}{27}\)
<=> \(-\left(3x-\frac{7}{9}\right)^3=\left(\frac{2}{3}\right)^3\)
<=> \(-\left(3x-\frac{7}{9}\right)=\left(\frac{2}{3}\right)\)
<=> x= \(\frac{1}{27}\) -------chỗ này tắt
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\(S=\dfrac{1}{3.5}+\dfrac{1}{5.7}+\dfrac{1}{7.9}+...+\dfrac{1}{97.99}\)
\(2S=\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+...+\dfrac{2}{97.99}\)
\(2S=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{97}-\dfrac{1}{99}\)
\(2S=\dfrac{1}{3}-\dfrac{1}{99}\)
\(2S=\dfrac{32}{99}\)
\(S=\dfrac{32}{99}:2\)
\(S=\dfrac{16}{99}\)
Cảm ơn bạn rất nhiều! Bạn đã cứu mình rùi! Xin trân thành cảm ơn!
Ta có : \(S=\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\)
\(\Rightarrow2S=2\left(\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\right)\)
\(\Rightarrow2S=\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}\)
\(\Rightarrow2S=\left(\frac{1}{3}-\frac{1}{5}\right)+\left(\frac{1}{5}-\frac{1}{7}\right)+...+\left(\frac{1}{97}-\frac{1}{99}\right)\)
\(\Rightarrow2S=\left(\frac{1}{3}-\frac{1}{99}\right)+\left[\left(\frac{1}{5}+...+\frac{1}{97}\right)-\left(\frac{1}{5}+\frac{1}{7}+...+\frac{1}{97}\right)\right]\)
\(\Rightarrow2S=\left(\frac{33}{99}-\frac{1}{99}\right)+0\)
\(\Rightarrow2S=\frac{32}{99}\)
\(\Rightarrow S=\frac{32}{99}\div2\)
\(\Rightarrow S=\frac{16}{99}\)
\(S=\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+...+\frac{1}{97.99}\)
\(S=\frac{1}{2}.\left(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}\right)\)
\(S=\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\right)\)
\(S=\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{99}\right)\)
\(S=\frac{1}{2}.\frac{32}{99}=\frac{16}{99}\)
2 . 125 . 18 + 36 . 252 + 4 . 233 . 9
=250 . 18 + 36 . 252 + 4 . 233 . 9
=4500 + 36 . 252 + 4 . 233 . 9
=4500 + 9072 + 4 . 233 . 9
= 13572 + 4 . 233 . 9
=13576 . 233 . 9
= 3163208 . 9
=28468872
k nhà mik làm bài này mệt lắm đó!!!!!!!! phù phù huhu
2.125.18+36.252+4.233.9 = 36.125+36.252+36.233
= 36(125+252+233)
= 36.610
= 21960
k cho mk nha.