15^3+5.15^2-5^3 / 18^3+6.18^2-6^3

=3375+5.225-125 /5832+6.324-216

=3375+1125-125 /5832+1944-216

=4500-125 /7826-216

=4375 /7610

=875 /1522

mk ko bt viết phần nên viết phần bằng dấu gạch / nhé.mk cx ko bt đúng hay sai đâu nhé

a) 13/60

b)43/4

 \(\frac{4}{5}+\frac{-7}{15}.1,25\)

\(=\frac{4}{5}+\frac{-7}{12}\)

\(=\frac{13}{60}\)

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a)  \(\frac{4}{5}\)+\(\frac{-7}{15}\) x  \(1,25\)

= \(\frac{4}{5}\)+ \(\frac{-7}{15}\)x   \(\frac{5}{4}\)

= \(\frac{4}{5}\)+\(\frac{-7}{12}\)

= \(\frac{48}{60}\)+ \(\frac{-35}{60}\)

=  \(\frac{13}{60}\)

b \(\frac{2}{5}\)+ \(\frac{3}{5}\)x  \(\left(4\frac{1}{2}-3,25\right)\)

= \(\frac{2}{5}\)+\(\frac{3}{5}\)x \(\left(\frac{9}{2}-\frac{13}{4}\right)\)

=\(\frac{2}{5}\)+\(\frac{3}{5}\)x\(\frac{5}{4}\)

=\(\frac{2}{5}\)+\(\frac{3}{4}\)

= \(\frac{8}{20}\)+\(\frac{15}{20}\)

=\(\frac{23}{20}\)

516 x 2,15=1109,4

2,1655:50,4331

...

a, 516 x 2,15 = 1109,4

b, 2,1655 : 5 = 0,4331

c, \(\frac{15}{4}\)x \(\frac{8}{3}\)x \(\frac{16}{25}\)x \(\frac{1}{5}\)

= 10 x \(\frac{16}{25}x\frac{1}{5}\)

= \(\frac{32}{5}x\frac{1}{5}\)

= \(\frac{32}{25}\)

d, \(\frac{3}{7}:\frac{5}{4}x\frac{3}{5}\)

= \(\frac{3}{7}x\frac{4}{5}x\frac{3}{5}\)

= \(\frac{12}{35}x\frac{3}{5}\)

= \(\frac{36}{175}\)

a, 516x2,15=1109,4

b, 2,1655 : 5=0,4331

c, 15/4 x 8/3 x 16/25 x 1/5

=10x16/25 x 1/5

=6,4x1/5

=1.28

d, 3/7 : 5/4 x 3/5=12/35x3/5=36/175

45-|-15|:3

=45-15 :3

=45-5

=40

45 - | -15 | : 3

= 45 - 15 : 3

= 45 - 5 

= 40

\(45-|-15|\div3\)

\(=45-15\div3\)

\(=45-5\)

\(=40\)

Tách hai dấu ngoặc thành hai vế A và B

Ta có : 

A=5.4¹⁵.9⁹-4.3²⁰.8⁹=5.2³⁰.3¹⁸-2².2²⁷.3²⁰

=2²⁹.3¹⁸(2.5-3²)=2²⁹.3¹⁸

B=5.2⁹.6¹⁹-7.2²⁹.27⁶=5.2⁹.2¹⁹.3¹⁹-7.2²⁹.3¹⁸

=2²⁸.3¹⁸(5.3-7.2)=2²⁸.3¹⁸

=>A:B=2²⁹.3¹⁸:2²⁸:3¹⁸=2

a,3/7 +1/2-[-3]/70

=13/14 -[-3]/70

=65/70 -[-3]/70

=34/35

b,3/5+-1/25 -35/100

=14/25 - 35/100

=56 /100 -35/100

= 21/100

c ,5/12 -3/-16+3/4

=29/48 +3/4

= 29/48 +36/48

=65/48

d, 5/15 +4/-12 +1/7 -1/-6

= 1/3 +1/-3 +1/7-1/-6

=0+1/7-1/-6

= 13/42

A.\(\dfrac{3}{7}+\dfrac{1}{2}+\dfrac{\left(-3\right)}{70}\)

=\([\dfrac{30}{70}+\dfrac{\left(-3\right)}{70}]\)+\(\dfrac{1}{2}\)

= \(\dfrac{27}{70}+\dfrac{35}{70}\)

=\(\dfrac{62}{70}=\dfrac{31}{35}\)

B.\(\dfrac{3}{5}+\dfrac{-1}{25}-\dfrac{35}{100}\)

=\(\dfrac{60}{100}+\dfrac{-4}{100}-\dfrac{35}{100}\)

=\(\dfrac{60+\left(-4\right)-35}{100}\)

=\(\dfrac{21}{100}\)

C.\(\dfrac{5}{12}-\dfrac{3}{-16}+\dfrac{3}{4}\)

=\(\left(\dfrac{5}{12}+\dfrac{9}{12}\right)-\dfrac{-3}{16}\)

=\(\dfrac{7}{6}-\dfrac{-3}{16}\)

=\(\dfrac{56}{48}-\dfrac{-9}{48}\)=\(\dfrac{65}{48}\)

D.\(\dfrac{5}{15}+\dfrac{4}{-12}+\dfrac{1}{7}-\dfrac{1}{-6}\)

=\(\dfrac{1}{3}+\dfrac{1}{7}+(\dfrac{-2}{6}-\dfrac{-1}{6})\)

=\(\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{-1}{6}\)

=\((\dfrac{1}{3}+\dfrac{-1}{6})+\dfrac{1}{7}\)

=\(\dfrac{1}{6}+\dfrac{1}{7}\)=\(\dfrac{13}{42}\)

\(\left(3^{15}+3^{16}+3^{17}\right):\left(3^{11}+3^{12}+3^{13}\right)=3^4.\left(3^{11}+3^{12}+3^{13}\right):\left(3^{11}+3^{12}+3^{13}\right)=3^4=81\)

\(\left(3^{15}+3^{16}+3^{17}\right):\left(3^{11}+3^{12}+3^{13}\right)\)

\(=3^4\left(3^{11}+3^{12}+3^{13}\right):\left(3^{11}+3^{12}+3^{13}\right)\)

\(=3^4=81\)

(3¹⁵+3¹⁶+3¹⁷) : (3¹¹+3¹²+3¹³)

=3⁴(3¹¹+3¹²+3¹³) : (3¹¹+3¹²+3¹³)

=3⁴=81

\(A=\left(x+1\right)\left(x+3\right)\left(x+5\right)\left(x+7\right)+15\)

\(A=\left[\left(x+1\right)\left(x+7\right)\right]\left[\left(x+3\right)\left(x+5\right)\right]+15\)

\(A=\left(x^2+8x+7\right)\left(x^2+8x+15\right)+15\)

Đặt \(a=x^2+8x+11\)

\(\Rightarrow A=\left(a-4\right)\left(a+4\right)+15\)

\(\Leftrightarrow A=a^2-16+15\)

\(\Leftrightarrow A=a^2-1\)

Thay a vào A ( :v ) ta có :

\(A=\left(x^2+8x+11\right)^2-1\)

\(A=\left(x^2+8x+11+1\right)\left(x^2+8x+11-1\right)\)

\(A=\left(x^2+8x+12\right)\left(x^2+8x+10\right)\)

\(A=\left(x^2+2x+6x+12\right)\left(x^2+8x+10\right)\)

\(A=\left[x\left(x+2\right)+6\left(x+2\right)\right]\left(x^2+8x+10\right)\)

\(A=\left(x+6\right)\left(x+2\right)\left(x^2+8x+10\right)⋮x+6\left(đpcm\right)\)

\(\dfrac{1}{4}-\dfrac{1}{3}+\dfrac{5}{12}\\ =\dfrac{3}{12}-\dfrac{4}{12}+\dfrac{5}{12}\\ =\dfrac{3-4+5}{12}\\ =\dfrac{4}{12}\\ =\dfrac{1}{3}\)