Rút gọn các phân số sau
a) 484/-860
b) 14.20-70.13/21.10+7.80
c) -10.21.35/15.(-14).(-4)
d) (-4)^3.27^2.(-10)^3/8^3.(-9)^2.25^2
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b1 -10/14
b2 -4/5
b3
a 2/9-7/8.x=1/3
7/8.x=2/9-1/3=-1/9
x=-1/9:-7/8=8/63
b 23/7.x-1/8=11/4
23/7.x=11/4+1/8=23/8
x=23/8:23/7=7/8
b4
Quyển truyện cs số trang:
36:(1−1/4−9/20)=120(trang)
a) 2√18 - 4√50 + 3√32
= 6√2 - 20√2 + 12√2
= -2√2
b) √(√8 - 4)² + √8
= 4 - √8 + √8
= 4
c) √(14 - 6√5) + √(6 + 2√5)
= √(3 - √5)² + √(√5 + 1)²
= 3 - √5 + √5 + 1
= 4
\(a,2\sqrt{18}-4\sqrt{50}+3\sqrt{32}\\ =6\sqrt{2}-20\sqrt{2}+12\sqrt{2}=-2\sqrt{2}\\ b,\sqrt{\left(\sqrt{8}-4\right)^2}+\sqrt{8}\\ =4-\sqrt{8}+\sqrt{8}\\ =4\\ c,\sqrt{14-6\sqrt{5}}+\sqrt{6+2\sqrt{5}}\\ =\sqrt{\left(3+\sqrt{5}\right)^2}+\sqrt{\left(\sqrt{5}+1\right)^2}=3+\sqrt{5}+\sqrt{5}+1\\ =4+2\sqrt{5}\)
Bài 1:
a: =-3/7
b: =-3/5
c: =1/13
d: =-1/2
Bài 2:
a: \(=\dfrac{21\cdot11}{22\cdot9}=\dfrac{1}{2}\cdot\dfrac{7}{3}=\dfrac{7}{6}\)
b: \(=\dfrac{49\cdot8}{10}=\dfrac{196}{5}\)
a) \(\frac{1.3+3.5+5.7+7.9}{3.6+9.10+15.14+21.18}\)
= \(\frac{1.3+3.5+5.7+7.9}{1.3.2.3+3.5.2.3+5.7.2.3+7.9.2.3}\)
= \(\frac{1.3+3.5+5.7+7.9}{1.3.6+3.5.6+5.7.6+7.9.6}\)
= \(\frac{1.3+3.5+5.7+7.9}{6.\left(1.3+3.5+5.7+7.9\right)}=\frac{1}{6}\)
Dấu "." là dấu nhân cấp 2
b) \(\frac{1.2+2.3+3.4+4.5}{3.6+6.9+9.12+12.15}\)
= \(\frac{1.2+2.3+3.4+4.5}{1.2.3.3+2.3.3.3+3.4.3.3+4.5.3.3}\)
= \(\frac{1.2+2.3+3.4+4.5}{1.2.9+2.3.9+3.4.9+4.5.9}\)
= \(\frac{1.2+2.3+3.4+4.5}{9.\left(1.2+2.3+3.4+4.5\right)}=\frac{1}{9}\)
Dấu "." là dấu nhân cấp 2
c) \(\frac{0,3+\frac{3}{7}+\frac{3}{11}}{0,4+\frac{4}{7}+\frac{4}{11}}\)= \(\frac{\frac{3}{10}+\frac{3}{7}+\frac{3}{11}}{\frac{4}{10}+\frac{4}{7}+\frac{4}{11}}\)= \(\frac{3.\left(\frac{1}{10}+\frac{1}{7}+\frac{1}{11}\right)}{4.\left(\frac{1}{10}+\frac{1}{7}+\frac{1}{11}\right)}=\frac{3}{4}\)
Bài 1:
a) \(\dfrac{-5}{6}\ne\dfrac{10}{-14}\left(\dfrac{10}{-14}=-\dfrac{5}{7}\right).\)
b) \(\dfrac{-15}{-60}\ne\dfrac{-3}{12}\left(\dfrac{-15}{-60}=\dfrac{1}{4}\right).\)
Bài 2:
a) \(\dfrac{20}{-140}=-\dfrac{1}{7}.\)
b) \(\dfrac{4.18}{9.12}=\dfrac{72}{108}=\dfrac{2}{3}.\)
c) \(\dfrac{17.25-17.3}{2.\left(-15\right)}=\dfrac{17.\left(25-3\right)}{-30}=-\dfrac{17.22}{30}=\dfrac{374}{30}=\dfrac{187}{15}.\)
Bài 3:
a) \(\dfrac{-3}{5}< \dfrac{4}{-7}.\)
b) \(\dfrac{-4}{21}>\dfrac{-7}{35}.\)
c) \(\dfrac{-7}{24}>\dfrac{-2}{3}.\)
d) \(\dfrac{-52}{167}< \dfrac{-3}{-4}.\)
a \(\dfrac{-2}{5}\)
b -1
c \(\dfrac{2}{5}\)
d \(\dfrac{-18}{11}\)
a)\(\frac{484}{-860}=\frac{121}{215}\)
b)\(\frac{14.20-70.13}{21.10+7.80}=\frac{7.2.10.2-7.10.13}{7.3.10+7.8.10}=\frac{7.4.10-7.10.13}{7.3.10+7.8.10}=\frac{7.10.\left(4-13\right)}{7.10.\left(3+8\right)}=\frac{-9}{11}\)
c)\(\frac{-10.21.35}{15.\left(-14\right).\left(-4\right)}=\frac{-2.5.3.7.7.5}{3.5.7.\left(-2\right).\left(-4\right)}=\frac{35}{-4}\)
d)\(\frac{\left(-4\right)^3.27^2.\left(-10\right)^3}{8^3.\left(-9\right)^2.25^2}=\frac{\left(-2^2\right)^3.\left(3^3\right)^2.\left(-2.5\right)^3}{\left(2^3\right)^3.\left[\left(-3\right)^2\right]^2.\left(5^2\right)^2}=\frac{-2^5.3^5.\left(-2\right)^3.5^3}{2^6.\left(-3\right)^4.5^4}=\frac{2^2.3}{5}=\frac{4.3}{5}=\frac{12}{5}\)
a,\(\frac{484}{-860}=\frac{484:\left(-4\right)}{-860:\left(-4\right)}=\frac{-121}{215}\)
b,\(\frac{14.20-70.13}{21.10+7.80}\)\(=\frac{280-910}{210+560}=\frac{-630}{770}=\frac{-9}{11}\)
c,\(\frac{-10.21.35}{15.\left(-14\right).\left(-4\right)}=\frac{1.\left(-3\right).35}{3.2.2}=\frac{105}{12}=8\frac{3}{4}\)
d,tự làm