Rút gọn:10*11+50*55+70*77/11*12+55*60+77*84
10×11+50×44+70×55 phần 11×12+55×60+77×84
mk ko bt sorry
ai vậy thì k mk nha
1+2+3+4+5+6+7+8+9=
10+20+39+40+50+60+70+80+90=
11+22+33+44+55+66+77+88+99=
Tkk cho đừng quên kb nha hjjjj
1+2+3+4+5+6+7+8+9=45
10+20+39+40+50+60+70+80+90=459(Chắc bạn bấm nhầm 30->39)
11+22+33+44+55+66+77+88+99=495
b1:rút gọn
a) \(\frac{10\cdot11+50\cdot55+70\cdot77}{11\cdot12+55\cdot60+77\cdot84}\) b)\(\frac{1\cdot3\cdot5\cdot........\cdot49}{26\cdot27\cdot28\cdot......\cdot50}\)
(x-9)/55 + (x-10)/66 = (x-11)/77 + (x-12)/88
\(\dfrac{x-9}{55}+\dfrac{x-10}{66}=\dfrac{x-11}{77}+\dfrac{x-12}{88}\\ \Leftrightarrow\left(\dfrac{x-9}{55}+\dfrac{1}{11}\right)+\left(\dfrac{x-10}{66}+\dfrac{1}{11}\right)-\left(\dfrac{x-11}{77}+\dfrac{1}{11}\right)-\left(\dfrac{x-12}{88}+\dfrac{1}{11}\right)=0\)
\(\Leftrightarrow\left(\dfrac{x-9}{55}+\dfrac{5}{55}\right)+\left(\dfrac{x-10}{66}+\dfrac{6}{66}\right)-\left(\dfrac{x-11}{77}+\dfrac{7}{77}\right)-\left(\dfrac{x-12}{88}+\dfrac{8}{88}\right)=0\)
\(\Leftrightarrow\dfrac{x-4}{55}+\dfrac{x-4}{66}-\dfrac{x-4}{77}-\dfrac{x-4}{88}=0\)
\(\Leftrightarrow\left(x-4\right)\left(\dfrac{1}{55}+\dfrac{1}{66}-\dfrac{1}{77}-\dfrac{1}{88}\right)=0\\ \Leftrightarrow x=4\left(vì.\dfrac{1}{55}+\dfrac{1}{66}-\dfrac{1}{77}-\dfrac{1}{88}\ne0\right)\)
bài 1 . tính nhanh
a, 39 + 11-16 + 77 + 88 + 55 -11 + 200 =
b, 60 - 10 : 2 -3 + 100
tính nhanh:
11+22+33+44+55+66+77+88+99
10+20+30+40+50
11+22+33+44+55+66+77+88+99
= ( 11 + 88 ) + ( 22 + 77 ) + ( 33 + 66 ) + ( 44 + 55 ) + 99
= 99 + 99 + 99 + 99 + 99
= 99 x 5
= 495
10+20+30+40+50
= ( 10 + 40 ) + ( 20 + 30 ) + 50
= 50 + 50 + 50
= 50 x 3
= 150
K mình nha mình nhanh nhất đó!
ai k mik mik ks lại
11+22+33+44+55+66+77+88+99
=(11+99)+(22+88)+(33+77)+(44+66)+55
=110+110+110+110+55
=110*4+55
=440+55
=495
10+20+30+40+50
=(10+50)+(20+40)+30
=60+60+30
=60*2+30
=120+30
=150
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 * 55 * 56 * 57 * 58 * 59 * 60 * 61 * 62 * 63 * 64 * 65 * 66 * 67 * 68 * 69 * 70 * 71 * 72 * 73 * 74 * 75 * 76 * 77 * 78 * 79 * 80 * 81 * 82 * 83 * 84 * 85 * 86 * 87 * 88 * 89 * 90 * 91 * 92 * 93 * 94 * 95 * 96 * 97 * 98 * 99 * 100 bằng bao nhiêu?
RÚT GỌN PHÂN SỐ 30/100= 55/77= 234/765= 8/10000
\(\dfrac{30}{100}=\dfrac{30:10}{100:10}=\dfrac{3}{10}\)
\(\dfrac{55}{77}=\dfrac{55:11}{77:11}=\dfrac{5}{7}\)
\(\dfrac{234}{765}=\dfrac{234:9}{765:9}=\dfrac{26}{85}\)
\(\dfrac{8}{10000}=\dfrac{8:8}{10000:8}=\dfrac{1}{1250}\)
Cách làm bài này
11+22+33+44+55+55+66+77+88+99
(11+99)+(22+88)+(33+77)+(44+66)+(55+55)=110+110+110+110+110=550
11 + 22 + 33 + 44 +55 +66 +77 +88 +99
= 495
11+22+33+44+55+66+77+88+99=495
kết bn với tui đi