Question

СРОЧНЯК ПОМОГИТЕ!!
розв'яжіть систему рівнянь

Answer 1

$\left \{ {{4x+y=5.} \atop {x^2-y=7.}} \right. \left \{ {{y=5-4x.} \atop {x^2-y=7.}} \right. \\x^2-(5-4x)=7.\\x^2-5+4x-7=0.\\x^2+4x-12=0.\\D = b^2 - 4ac = 4^2 - 4*1*(-12) = 16 + 48 = 64.\\\sqrt{D} = 8.\\x_{1} =-\frac{-12}{2} =-6.\\x_{2} =-\frac{4}{2} =2.\\y_{1} =5-4*(-6)=29.\\y_{2} =5-4*2=-3.\\(x_{1} ,y_{1} )=(-6,29).\\(x_{2} ,y_{2} )=(2;-3).$