Х+у=48 х*у=15   х=? у=? 

х+у=48 ху=15   x=48-y xy=15   (48-y)y=15 48y-y²=15 y²-48y+15=0 Δ=(-48)²-4*1*15 Δ=2304-60 Δ=2244 √Δ=2√561   y₁=(-(-48)-2√561)/(2*1) y₁=(48-2√561)/2 y₁=24-√561   y₂=(-(-48)+2√561)/(2*1) y₂=(48+2√561)/2 y₂=24+√561   x₁=48-(24-√561) x₁=48-24+√561 x₁=24+√561   x₂=48-(24+√561) x₂=48-24-√561 x₂=24-√561   24+√561 и 24-√561