15 . (–2) . (–5) . (–6)

= [15 . (–2)] . [(–5) . (–6)]

= [– (15.2)] . (5.6)

= (–30) . 30

= –900

a, 

15.(-2).(-5).(-6)

=  (-30).(-5).(-6)

=  150 . (-6)

= -900

b,    

4.7.(-11).(-2)

= 28 .(-11).(-2)

= (-308) . (-2)

= 616

Thực hiện các phép tính :

a) 15.(-2).(-5).(-6)

= 15. (-6). (-2). (-5)

= -90. 10

= -900

b)4.7.(-11).(-2)

= 28. 22

= 616

\(a) 15.(-2).(-5).(-6) \)

\(= [15.(-2)].(-5).(-6)\)

\(= [(- 30) . (-5)].(-6)\)

\(= 150 . (-6)\)

\(= -900\)

\(b)4.7.(-11).(-2)\)

\(= (4.7).(-11).(-2) \)

\(= 28.(-11).(-2)\)

\(= -308.(-2)\)

\(= 616\)

`a,5 xx (-7)+(-2) xx (-5)`

`=5 xx (-7)+5 xx 2`

`= 5 xx (2-7)`

`=5 xx (-5)`

`=-25`

`b,5 xx (-9)+(-2) xx 3`

`=3 xx (-15)+3 xx (-2)`

`=3 xx (-15-2)`

`=3 xx (-17)`

`=-51`

`c,6 xx (-5)^2+3 xx (-15)`

`=2 xx 3 xx 25+3 xx (-15)`

`=3 xx 75-3 xx 15`

`=3 xx (75-15)`

`=3 xx 60`

`=180`

a) 5×(-7) +(-2) ×(-5)

=5.(-7)+2.5

=5.(-7+2)

=5.(-5)=-25

\(B=\left(\dfrac{4}{1-\sqrt{5}}+\dfrac{1}{2+\sqrt{5}}-\dfrac{4}{3-\sqrt{5}}\right)\left(\sqrt{5}-6\right)\)

\(B=\left[\dfrac{4\left(1+\sqrt{5}\right)}{\left(1-\sqrt{5}\right)\left(1+\sqrt{5}\right)}+\dfrac{2-\sqrt{5}}{\left(2+\sqrt{5}\right)\left(2-\sqrt{5}\right)}-\dfrac{4\left(3+\sqrt{5}\right)}{\left(3-\sqrt{5}\right)\left(3+\sqrt{5}\right)}\right]\left(\sqrt{5}-6\right)\)

\(B=\left[\dfrac{4\left(1+\sqrt{5}\right)}{1-5}+\dfrac{2-\sqrt{5}}{4-5}-\dfrac{4\left(3+\sqrt{5}\right)}{9-5}\right]\left(\sqrt{5}-6\right)\)

\(B=\left[-\dfrac{4\left(1+\sqrt{5}\right)}{4}-\dfrac{2-\sqrt{5}}{1}-\dfrac{4\left(3+\sqrt{5}\right)}{4}\right]\left(\sqrt{5}-6\right)\)

\(B=\left(-1-\sqrt{5}-2+\sqrt{5}-3-\sqrt{5}\right)\left(\sqrt{5}-6\right)\)

\(B=\left(-\sqrt{5}-6\right)\left(\sqrt{5}-6\right)\)

\(B=-\left(\sqrt{5}+6\right)\left(\sqrt{5}-6\right)\)

\(B=-\left(5-36\right)\)

\(B=-\left(-31\right)\)

\(B=31\)

_____________________________

\(\sqrt{48}-\dfrac{\sqrt{21}-\sqrt{15}}{\sqrt{7}-\sqrt{5}}+\dfrac{2}{\sqrt{3}+1}\)

\(=4\sqrt{3}-\dfrac{\sqrt{3}\left(\sqrt{7}-\sqrt{5}\right)}{\sqrt{7}-\sqrt{5}}+\dfrac{2\left(\sqrt{3}-1\right)}{\left(\sqrt{3}-1\right)\left(\sqrt{3}+1\right)}\)

\(=4\sqrt{3}-\sqrt{3}-\dfrac{2\left(\sqrt{3}-1\right)}{2}\)

\(=3\sqrt{3}-\sqrt{3}+1\)

\(=2\sqrt{3}+1\)

a)

15 . ( - 2 ) . ( - 5 ) . ( - 6 )

= [( 15 . ( - 2 )] . [( - 5 ) . ( - 6 )]

= - 30 . 30

= - 900

b)

4 . 7 . ( - 11 ) . ( - 2 )

= ( 4 . 7 ) . [( - 11 ) . ( - 2 )]

= 28 . 22

= 616 

a)15. (-2).(-5).(-6)

=(-30).(-5).(-6)

=150.(-6)

=-900

b)4.7.(-11).(-2)

=28.(-11).(-2)

=(-308).(-2)

=616

a , 15 . ( - 2 ) . ( - 5 ) . ( - 6 ) = ( - 30 ) . 30 = -90

b , 4 . 7 . ( - 11 ) . ( - 2 ) = 28 . 22 = 616

=\(\left[\dfrac{\left(0,4.2\right)^5}{\left(0,4\right)^6}+\dfrac{2^9.2^6.3^8}{\left(3.2\right)^6.2^9}\right]=\left[\dfrac{\left(0,4\right)^5.2^5}{\left(0,4\right)^6}+\dfrac{2^6.3^8}{3^6.2^6}\right]\)

=\(\left[\dfrac{2^5}{0,4}+3^2\right]\)

=\(\left[80+9\right]=89\)

\(\left[\dfrac{\left(2.0,4\right)^5}{0,4,0,4^5}+\dfrac{2^{15}.3^8}{3^6.2^6.2^9}\right]\div\dfrac{3^{20}.5^{30}}{3^{15}.5^{30}}\)

\(=\left[\dfrac{2^5.0.4^5}{0,4.0,4^5}+\dfrac{2^{15}.3^8}{3^6.2^{15}}\right]\div3^5\)

\(=\left[\dfrac{2^5}{0,4}+3^2\right]\div243\)

\(=80+\left(3^5\div3^2\right)\)

\(=80+3^3\)

\(=80+27\)

\(=107\)

15.{32:[6-5+5(9:3)]}

=15.{32:[1+5.3]}

=15.{32:[1+15]}

=15.{32:16}

=15.2

=30

[(-4) . 6 - (15 - 11)2] - [(-15) : 3]3

= [-24 - 4 . 2] - (-5) . 3

= [-24 - 8] - (-15)

= -32 + 15

= -16

Nhầm -17 ms đúng=)

[ (-4).6 - (15 - 11).2] - [ (-15):3)].3

= [-24 - 4.2] + 15:3.3

= [ -24 - 8] + 15

= - 32 + 15

= - 17 

\(\frac{3}{5}:\left(-\frac{1}{15}-\frac{1}{6}\right)+\frac{3}{5}:\left(-\frac{1}{3}-\frac{16}{15}\right)\)

\(=\frac{3}{5}:\left(-\frac{7}{30}\right)+\frac{3}{5}:\left(-\frac{7}{5}\right)\)

\(=\frac{3}{5}.\left(-\frac{30}{7}\right)+\frac{3}{5}.\left(-\frac{5}{7}\right)\)

\(=\frac{3}{5}\left(-\frac{30}{7}-\frac{5}{7}\right)\)

\(=\frac{3}{5}.\left(-\frac{35}{7}\right)\)

\(=-3\)