Question

вычислите:

п.с 91(в третьей)+28(в третьей)/ 119 записано дробью

Answer 1

$(65^{2}-16^{2})/ ( frac{(91^{2}+28^{2})}{119} - 91*28 ) =$ 1

 

$frac{(91^{2}+28^{2})}{119} - 91*28 ) = frac{(91+28)(91^{2}-91*28+28^{2})}{119} - 91*28 ) =$$frac{119(91^{2}-91*28+28^{2})}{119} - 91*28 ) = (91^{2}-91*28+28^{2}) - 91*28 ) =$$91^{2}-2*91*28+28^{2} = (91-28)^{2} = 63^{2}$

 

$frac{65^{2}-16^{2}}{63^{2}} = frac{(65-16)(65+16)}{63^{2}} = frac{49*81}{63^{2}}=frac{3969}{3969} = 1$