78-2×(x-11)=60.
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a,12x-180+10x-20+39x-2340+65x-4420=780
126x-6960=780
126x=7740
x=430/7
\(\frac{\left(120+60\right)}{12}=\frac{120}{12}+\frac{60}{12}=10+5=15\)
\(78\cdot31+78\cdot17+78\cdot24+22\cdot72=78\left(31+17+24\right)+22\cdot72\)
\(=78\cdot72+22\cdot72=72\left(78+22\right)=72\cdot100=7200\)
\(997+86=997+\left(83+3\right)=\left(997+3\right)+83\)
\(=1000+83=1083\)
\(5\cdot25\cdot2\cdot37\cdot4=\left(5\cdot2\right)\cdot\left(25\cdot4\right)\cdot37\)
\(=10\cdot100\cdot37=37000\)
\(558+336+442+664=\left(558+442\right)+\left(336+664\right)\)
\(=1000+1000=2000\)
5 x 25 x 2 x 37 x 4
= ( 5 x 2 ) x ( 25 x 4 ) x 37
= 10 x 100 x 37
= 1000 x 37
= 37000
36 x 12 + 36 x 45 + 36 x 33
= 36 x (12 + 45 + 33)
= 36 x 90
= 3240
b) 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72
=78 x (31 + 24 + 17) + 22 x 72
= 78 x 72 + 22 x 72
= (78 + 22) x 72
= 100 x 72
= 7200
c) ( 34 - 17 )2 - 23 x 32
\(=17^2-8.9\)
\(=289-72\)
\(=217\)
a) x : 11 = 25
x = 25 x 11
x = 275
b) x : 11 = 78
x = 78 x 11
x = 858
1: 243^5=(3^5)^5=3^25
3*27^8=3*(3^3)^8=3^25
=>243^5=3*27^8
6: 125^5=(5^3)^5=5^15
25^7=(5^2)^7=5^14
=>125^5>25^7(15>14)
5: 78^12-78^11=78^11(78-1)=78^11*77
78^11-78^10=78^10*77
mà 11>10
nên 78^12-78^11>78^11-78^10
78-2×(x-11)=60
= 2 x ( x - 11 ) = 78 - 60
= 2 x ( x - 11 ) = 18
= x - 11 = 18 : 2
= x - 11 = 9
= x = 9 + 11
= x = 20
78 - 2 \(\times\) (x - 11) = 60
2 \(\times\) (x - 11) = 78 - 60
2 \(\times\) (x - 11) = 18
(x - 11) = 18 : 2
(x - 11) = 9
x = 9 + 11
x = 20.