(х+3)(у-2)+2х-3у+1=ху-2х+3у-6+2х-3у+1=ху-5
6 + 25/16 = 6 + 1 9/16 = 7 9/16
Или:
6 + 25/16 = 6 + 1,5625 = 7,5625
Tgx * ctgx = 1
ctgx = 1/tgx ===>
<span>2ctgx + ctgx = 3ctgx </span>
<span>2,4*1,6=(2+0,4)(2-0,4)=4-0,16=3,84
49*51=(50-1)(50+1)=2500-1=2499
86^2-14^2=(86-14)(86+14)=72*100=7200</span>