18. 25 + 35 + 15. 32 + 35. 49
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`@` `\text {Ans}`
`\downarrow`
`18*15 + 35 + 15*32 + 35*49`
`= 15 (18+32) + 35(1+49)`
`= 15*50 + 35*50`
`= 50*(15+35)`
`= 50*50`
`= 2500`
\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)
= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)
=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)
= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)
\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)
= \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)
= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)
= 1 + 1 + 1 = 3
\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)
= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!
`1,`
`a,`
`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`
`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`
`= 7/19 \times (8/23 + 15/23 + 1) + 1`
`= 7/19 \times 2 + 1`
`=14/19 + 1`
`= 33/19`
`b,`
`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`
`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`
`= 0,75 + 1 + 1 + 0,25`
`= (0,75 + 0,25) + 1 + 1`
`= 1+1+1=3`
`c,`
`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`
`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)
`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).
a) \(\dfrac{3}{35}+\dfrac{7}{20}+\dfrac{32}{35}+\dfrac{13}{20}\)
Áp dụng tính chất giao hoán, kết hợp của phép cộng, ta được:
\(\left(\dfrac{3}{35}+\dfrac{32}{35}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\)
\(=1+1\)
\(=2\)
b) \(\dfrac{18\cdot15\cdot56}{42\cdot27\cdot25}=\dfrac{2\cdot3\cdot3\cdot5\cdot3\cdot4\cdot2\cdot7}{2\cdot3\cdot2\cdot2\cdot3\cdot9\cdot5\cdot5}\)
\(=\dfrac{2\cdot2\cdot3\cdot3\cdot3\cdot4\cdot5\cdot7}{2\cdot2\cdot2\cdot3\cdot3\cdot5\cdot5\cdot9}=\dfrac{3\cdot2\cdot2\cdot7}{2\cdot5\cdot9}=\dfrac{42}{45}\)
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
\(18.15+35+15.32+35.4+9\)
\(=\left(18.15+15.32\right)+\left(35+35.4\right)+9\)
\(=\left[15.\left(18+32\right)\right]+\left[35.\left(1+4\right)\right]+9\)
\(=\left[15.50\right]+\left[35.5\right]+9\)
\(=750+175+9\)
\(=934\)
Bai nay la Phan so hay 2 bai riêng chu ban ghi vay ai ma biết lam the nao
\(a,\frac{-15}{32}.\left(\frac{-18}{25}\right).\left(\frac{-1}{2}\right)^2\)
\(=\frac{-15}{32}.\left(\frac{-18}{25}\right).\frac{1}{4}\)
\(=\frac{-15.\left(-18\right).1}{32.25.4}\)
\(=\frac{27}{320}\)
\(b,\frac{35}{34}.\left(\frac{-17}{39}\right).\frac{26}{45}\)
\(=\frac{35.\left(-17\right).26}{34.39.45}\)
\(=\frac{-7}{27}\)
18. 25 + 35 + 15. 32 + 35. 49
=450+35+480+1715
=485+480+1715
=965+1715
=2680
Ta có:
18.25 + 35 + 15.32 + 35.49
= 450 + 35 + 480 + 1715
= 2680