Решите 43 номер, пожалуйста.Нужно с решением и полными ответами.

А) 81*79=(80+1)(80-1)=80²-1²=6400-1=6399

б) 3,9*4,1=(4-0,1)(4+0,1)=4²-0.1²=16-0.01=15.99

в) 8 1/6* 7 5/6=(8+1/6)(8-1/6)=8²-(1/6)²=64-1/36=63 35/36

г)68²-2*68*8+8²=(68-8)²=60²=3600

д)76,4²+2*76.4*13.6+13.6²=(76.4+13.6)²=90²=8100

e)257²-143²=(257-143)(257+143)=114*400=45600

ж)21,3²-21.2²=(21.3-21.2)(21.3+21.2)=0.1*42.5=4.25

з) 72/(13²-11²)=72/(13-11)(13+11)=72/(2*24)=36/24=3/2=1.5

и)
$\frac{47^2-13^2}{16^2-2*16*18+18^2} = \frac{(47-13)(47+13)}{(16-18)^2} =\frac{34*60}{(-2)^2} =\frac{34*60}{4} =\frac{17*60}{2} =$
=17*30=210

к)
$\frac{49^2-13^2}{19^2+2*19*17+17^2} = \frac{(49-13)(49+13)}{(19+17)^2} = \frac{36*62}{36^2} =\frac{62}{36} = \frac{31}{18}=1 \frac{13}{18}$

л)
$\frac{92^2-48^2}{27^2-17^2} = \frac{(92-48)(92+48)}{(27-17)(27+17)} = \frac{44*140}{10*44} =\frac{140}{10} =14$

м)
$\frac{38^2-17^2}{47^2-19^2} = \frac{(38-17)(38+17)}{(47-19)(47+19)} = \frac{21*55}{28*66} = \frac{3*55}{4*66} =\frac{3*5}{4*6} =\frac{5}{4*2} =5/8=0.625$

н)
$\frac{79^2+73^2-49^2-55^2}{109^2-2*109*61+61^2} = \frac{(79^2-55^2)+(73^2-49^2)}{(109-61)^2} = \\ =\frac{(79-55)(79+55)+(73-49)(73+49)}{48^2} = \\ =\frac{24*134+24*122}{48*48} =\frac{24*2*67+24*2*61}{48*48} = \frac{48*67+48*61}{48*48} = \\ = \frac{48(67+61)}{48*48} = 128/48= 32/12=8/3=2 \frac{2}{3}$