Ответ:

это немаё решение

Объяснение:

begin{gathered}80a) left{begin{array}{l}x+y=2\x^2-y^2=100end{array}right left{begin{array}{l}x+y=2\(x-y)(x+y)=100end{array}right left{begin{array}{l}x+y=2\(x-y)cdot 2=100end{array}right\\\left{begin{array}{l}x+y=2\x-y=50end{array}right oplus ominus left{begin{array}{l}2x=52\2y=-48end{array}right left{begin{array}{l}x=26\y=-24end{array}right Otvet: (26;-24) .end{gathered}

begin{gathered}b) left{begin{array}{l}x+y=-5\x^2-y^2=5end{array}right left{begin{array}{l}x+y=-5\(x-y)(x+y)=5end{array}right left{begin{array}{l}x+y=5\-5, (x-y)=5end{array}right\\\left{begin{array}{l}x+y=-5\x-y=-1end{array}right oplus ominus left{begin{array}{l}2x=-6\2y=-4end{array}right left{begin{array}{l}x=-3\y=-2end{array}right Otvet: (-3;-2) .end{gathered}

begin{gathered}c) left{begin{array}{l}y-3x=0\x^2+y^2=40end{array}right left{begin{array}{l}y=3x\x^2+(3x)^2=40end{array}right left{begin{array}{l}y=3x\10x^2=40end{array}right\\\left{begin{array}{l}y=3x\x^2=4end{array}righty left{begin{array}{l}y=3x\x=pm 2end{array}rightend{gathered}

begin{gathered}1. left{begin{array}{l}y=3x\x=-2end{array}right left{begin{array}{l}y=-6\x=-2end{array}right\\\2. left{begin{array}{l}y=3x\x=2end{array}right left{begin{array}{l}y=6\x=2end{array}right\\\text{O}tvet: (-2;-6) , (2;6) .end{gathered}

begin{gathered}d) left{begin{array}{l}2x+y=0\xy=2end{array}right left{begin{array}{l}y=-2x\x(-2x)=2end{array}right left{begin{array}{l}y=-2x\-2x^2=2end{array}right left{begin{array}{l}y=-2x\x^2=-1end{array}right\\\text{O}tvet: varnothing , tak kak x^2geq 0 i x^2ne -1 .end{gathered}