\(31,8^2-2.31,8.21,8+21,8^2\)

\(=\left(31,8-21,8\right)^2=10^2=100\)

\(58,2^2+2.58,2.41,8+41,8^2\)

\(=\left(58,2+41,8\right)^2=100^2=10000\)

17,03 x 0,25 = 4,2575

140,76 : 204 = 0,69

10,6 : 4,24 = 2,5 

625,04 x 6,5 = 4062,76 

3696 : 6,72 = 550

125,76 : 1,6 = 78,6

21,8 x 3,4 = 74,12

28,8 : 3,75 = 7,68

24,36 : 6 = 4,06 

17.3

×

0.25

1,

\(a,=\sqrt{\left(21,8-18,2\right)\left(21,8+18,2\right)}\\ =\sqrt{3,6\cdot40}\\ =\sqrt{36\cdot4}\\ =\sqrt{36}\cdot\sqrt{4}\\ =6\cdot4\\ =24\)

\(b,=10\cdot\sqrt{\left(6,5-1,6\right)\left(6,5+1,6\right)}\\ =10\cdot\sqrt{4,9\cdot8,1}\\ =10\cdot\sqrt{49\cdot0,81}\\ =10\cdot\sqrt{49}\cdot\sqrt{0,81}\\ =10\cdot7\cdot0,9\\ =63\)

2,

\(A=7+4\sqrt{3}+\sqrt{3}-1\\ =6+5\sqrt{3}\\ B=7+2\sqrt{10}-\left(11+2\sqrt{10}\right)\\ =7+2\sqrt{10}-11-2\sqrt{10}\\ =-4\)

\(a,2,15+3,26+4,85+6,74\)

\(=\left(2,15+4,85\right)+\left(3,26+6,74\right)\)

\(=7+10=17\)

\(b,53,39+87,6+6,61+22,4\)

\(=\left(53,39+6,61\right)+\left(87,6+22,4\right)\)

\(=60+110=170\)

a) 1,986 x 21,8 - 1,986 x 16,4 - 1,986 x 4,6

= 1.986 x ( 21.8 - 16.4 - 4.6 )

= 1.986 x 0.8

= 1.5888

=1,5888

chúc bạn hok tốt

...................

a) [31,54 + 69,135]*83,26 

= 100,675*3,26

=328,2005

b) 541,6-3,08*46,07 + 95,548

=541,6-141,8956+95,548

=399,7044+95,548

=495,2524

 K NHA!!!!!!!!!!