Доска 10 на 10, следовательно 100.
(2+c)²-c(c-4) = (15/8)²+1/8*(-33/8) = 225/64 + (-33/64) = 192/64 = 3
<span>(3/7x-5/6)*1 2/13=2 1/2
</span><span>(3/7x-5/6)*15/13=5/2
</span>3/7x-5/6=5/2:15/13
3/7x-5/6=5/2*13/15
3/7x-5/6=1/2*13/3
3/7х-5/6=13/6
3/7х=13/6+5/6
3/7х=18/6
3/7х=3
х=3:3/7
х=3*7/3
х=7