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№4 2)c, 3)e, 4)a, 5)b
№5 1) climb walls or danсе
2)can swim, danсе or take photos (вроде так)
4 х ² + 6 х - 2 = (х - 1)²
[cos105⁰(cos277⁰sin172⁰-cos7⁰sin82⁰]/(2√2)⁻²=
=(2√2)²·cos105⁰·[1/2(sin(172⁰-277⁰)+sin(172⁰+277⁰))-1/2(sin(82⁰-7⁰)+sin(82⁰+7⁰))]=
=4·2·1/2·cos105⁰·(sin(-105⁰)+sin449⁰-sin75⁰-sin89⁰)=
=4·cos105⁰·(-sin105⁰+sin(2π+89⁰)-sin75⁰-sin89⁰)=
=-4·cos105⁰·sin105⁰-4·cos105⁰·sin75⁰=
=-2·sin210⁰-4·1/2·(sin(75⁰-105⁰)+sin(75⁰+105⁰)=
=-2sin(π+30⁰)-2[(sin(-30⁰)+sin180⁰)]=
=-2(-sin30⁰)-2[(-sin30⁰)+0]=2sin30⁰+2sin30⁰=4sin30⁰=4·(1/2)=2
2y+2x = 45, тогда y = (45-2x)/2
Приравняем уравнения :
1.5x = 22.5 - x
2.5x = 22.5
x = 9
y = 1.5x = 13.5
Графики пересекутся в точке (9;13.5)