C1: Tính
a,\(\dfrac{7}{8}+\dfrac{10}{16}\)
b,\(\dfrac{12}{4}+\dfrac{6}{5}\)
c,\(\dfrac{23}{9}x\dfrac{4}{7}\)
d,\(\dfrac{8}{9}:\dfrac{6}{4}\)
\(\dfrac{14+10}{16}=\dfrac{24}{16}\)
\(\dfrac{60+24}{20}=\dfrac{84}{20}\)
\(\dfrac{92}{63}\)
\(\dfrac{32}{54}\)
Bài 3 : Tính
a) 11/7 + 3/5 , 4 + 1/9 b) 21/5 - 5/8 , 2 - 11/15
c) 3/19 x 38/9 , 21/5 x 2 c) 7/3 : 4/9 , 12/7 : 3
a) = 76/35 ; 37/9
b) 143/40 ; 19/15
c) 2/3 ; 42/5
d) 21/4 ; 4/7
a, 11/7 + 3/5
= \(\dfrac{11x5}{7x5}+\dfrac{3x7}{5x7}=\dfrac{55}{35}+\dfrac{21}{35}=\dfrac{76}{35}\)
4 + 1/9
= \(\dfrac{4}{1}+\dfrac{1}{9}=\dfrac{4x9}{1x9}+\dfrac{1x1}{9x1}=\dfrac{36}{9}+\dfrac{1}{9}=\dfrac{37}{9}\)
b, 21/5 - 5/8
= \(\dfrac{21x8}{5x8}-\dfrac{5x5}{8x5}=\dfrac{168}{40}-\dfrac{25}{40}=\dfrac{143}{40}\)
2 - 11/15
=\(\dfrac{2}{1}-\dfrac{11}{15}=\dfrac{30}{15}-\dfrac{11}{15}=\dfrac{19}{15}\)
MIK LÀM ĐC NGẦN ĐẤY THUI BẸN THÔNG CẢM
Câu 3. Tính
a) ( - 11) x ( - 28) + (- 9) x 13
b) ( - 69 ) x ( - 31) - ( - 15) x 12
c) [16 - (- 5) ] x (-7)
d)[(- 4) x (- 9) - 6]x[(-12) - (-7)]
a: \(\left(-11\right)\cdot\left(-28\right)+\left(-9\right)\cdot13\)
\(=308-117\)
=191
b: \(\left(-69\right)\cdot\left(-31\right)-\left(-15\right)\cdot12\)
\(=2139-\left(-180\right)\)
=2139+180
=2319
c: \(\left[16-\left(-5\right)\right]\cdot\left(-7\right)\)
\(=\left(16+5\right)\cdot\left(-7\right)\)
\(=-7\cdot21=-147\)
d: \(\left[\left(-4\right)\cdot\left(-9\right)-6\right]\left[\left(-12\right)-\left(-7\right)\right]\)
\(=\left[36-6\right]\left[-12+7\right]\)
\(=30\cdot\left(-5\right)=-150\)
1.Thực hiện phép tính
a) \(\dfrac{4}{5}\) + \(\dfrac{6}{5}\) : \(\dfrac{7}{15}\) - \(\dfrac{3}{7}\)
b) \(\dfrac{9}{13}\) . \(\dfrac{5}{3}\) + \(\dfrac{-6}{13}\) .\(\dfrac{9}{13}\) - \(\dfrac{9}{13}\) . \(\dfrac{20}{13}\)
2.Tìm x,biết:
a) \(\dfrac{2}{5}\) . x - \(\dfrac{1}{3}\) = 1\(\dfrac{2}{3}\)
b) \(\dfrac{4}{9}\) - \(\dfrac{5}{9}\) : x = \(\dfrac{7}{3}\)
c) \(\dfrac{4}{5}\) . x + \(\dfrac{-7}{3}\) . x = \(\dfrac{\left(-2\right)^3}{5}\)
2.tính
a) 3/7 + 3/4 - 1/2 =
b) 6/11 + 2/9 x 12 =
c) 5/7 - 8/5 : 4 =
a) 3/7 + 3/4 - 1/2 =33/28-1/2=19/28
b) 6/11 + 2/9 x 12 =6/11+8/3=106/33
c) 5/7 - 8/5 : 4 =5/7-2/5=11/35
a) 3/7 + 3/4 - 1/2 = \(\dfrac{12}{28}+\dfrac{21}{28}-\dfrac{14}{28}=\dfrac{19}{28}\)
b) 6/11 + 2/9 x 12 = \(\dfrac{6}{11}+\dfrac{8}{3}=\dfrac{18}{33}+\dfrac{88}{33}=\dfrac{106}{33}\)
c) 5/7 - 8/5 : 4 = \(\dfrac{5}{7}-\dfrac{2}{5}=\dfrac{25}{35}-\dfrac{14}{35}=\dfrac{11}{35}\)
3/7 + 3/4 - 1/2 = 33/28 - 1/2 = 19/28
6/11 + 2/9 x 12 = 6/11+ 8/3 = 106/33
5/7 - 8/5 : 4 = 5/7 - 2/5 = 11/35
B= 5 x 2 mũ 9x 6 mũ 19 -7 x 2 mũ 29 x 27 mũ 6
rồi tính A:B
\(A=5\cdot4^{15}\cdot9^9-4\cdot3^{20}\cdot8^9\)
\(A=5\cdot\left(2^2\right)^{15}\cdot\left(3^2\right)^9-2^2\cdot3^{20}\cdot\left(2^3\right)^9\)
\(A=5\cdot2^{30}\cdot3^{18}-2^2\cdot3^{20}\cdot2^{27}\)
\(A=5\cdot2^{30}\cdot3^{18}-2^{29}\cdot3^{20}\)
\(A=2^{29}\cdot3^{18}\cdot\left(5\cdot2^1\cdot1-1\cdot3^2\right)\)
\(A=2^{29}\cdot3^{18}\cdot\left(5-9\right)\)
\(A=-2^2\cdot2^{29}\cdot3^{18}\)
\(A=-2^{31}\cdot3^{18}\)
_______________
\(B=5\cdot2^9\cdot6^{19}-7\cdot2^{29}\cdot27^6\)
\(B=5\cdot2^9\cdot2^{19}\cdot3^{19}-7\cdot2^{29}\cdot\left(3^3\right)^6\)
\(B=5\cdot2^{28}\cdot3^{19}-7\cdot2^{29}\cdot3^{18}\)
\(B=2^{28}\cdot3^{18}\cdot\left(5\cdot1\cdot3-7\cdot2\cdot1\right)\)
\(B=2^{28}\cdot3^{18}\cdot\left(15-14\right)\)
\(B=2^{28}\cdot3^{18}\)
Ta có: \(A:B\)
\(=\left(-2^{31}\cdot3^{18}\right):\left(2^{28}\cdot3^{18}\right)\)
\(=\left(-2^{31}:2^{28}\right)\cdot\left(3^{18}:3^{18}\right)\)
\(=-2^3\cdot1\)
\(=-8\)
tính
a)x+5=-2+11 b)-3x=-5+29
c)[x]-9=-2+17 d)[x-9]=-2+17
a)x+5= 9
x=9-5
x=4
b) -3x=24
x=24:-3
x=-8
c) [x]-9=15
[x]=15+9
[x]=24
x=24
d)[x-9]=-2+17
[x-9]=15
[x]=15+9
[x]=24
x=24
a) \(x+5=-2+11\) b)\(-3x=5+29\)
\(\Rightarrow x=-2+11-5\) \(\Rightarrow-3x=24\)
\(\Rightarrow x=4\) \(\Rightarrow-8\)
c)\(\left|x\right|-9=-2+17\) d)\(\left|x-9\right|=-2+17\)
\(\left|x\right|=15+9\) \(\left|x-9\right|=15\)
\(\left|x\right|=24\) \(x-9=15\) hoặc \(x-9=15\)
x = 24 hoặc - 24 \(x=24\) hoặc \(x=-6\)
Bài 1: Tính
a) \(\dfrac{9}{5}+\dfrac{2}{5}\) x \(\dfrac{4}{6}\) b) \(\dfrac{3}{8}\) x 2 - \(\dfrac{6}{7}\) x \(\dfrac{1}{3}\)
Bài 2: Tính bằng cách thuận tiện nhất:
a) \(\dfrac{11}{23}+\dfrac{2}{23}+\dfrac{9}{23}+\dfrac{18}{23}\) b)\(\dfrac{25}{12}+\dfrac{17}{6}-\dfrac{15}{36}-\dfrac{15}{6}\)
Bài 3: Một hình chữ nhật có chiều rộng là \(\dfrac{3}{5}\) m và bằng một nửa chiều dài. Tính diện tích hình chữ nhật đó.
tính
a)(-12)+(-9)
b)3^2 x 24 +3^2 x76
9^5 -3^2x3
tìm x
a)x-12=-28
b)20+8x(x+3)=5^2x4
)9^5 :9^3-3^2x3
Bài 1:
a: =-21
b: =9x100=900
