Ответ:
Объяснение:
с) 2^( 3x+ y)= 2^9, 3x+y=9, y=9-3x, x+2(9-3x)=(9-3x)^2-x^2 +3 (^ -знак степени), x+18-6x=81-54x+9x^2-x^2 +3, 8x^2-49x+66=0,
D=2401-2112=289=17^2,, x=49+-17 /16, x1=32/16=2, x2=66/16=33/8,
y1=9-3*2=3, y2=9-66/8=72-99 /8=-27/8, отв. (2;3) u (33/8; -27/8)
d) log(xy) 4=log4 4, xy=4, y=7+2x, x(7+2x)=4, 7x+2x^2=4,
2x^2+7x-4=0, D=81, x=-7+-9 /4, x1=-4, x2=1/2, y1=7-8=-1, y2=7+1=8
отв (-4;-1) u (1/2;8)
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Answers & Comments
Ответ:
Объяснение:
с) 2^( 3x+ y)= 2^9, 3x+y=9, y=9-3x, x+2(9-3x)=(9-3x)^2-x^2 +3 (^ -знак степени), x+18-6x=81-54x+9x^2-x^2 +3, 8x^2-49x+66=0,
D=2401-2112=289=17^2,, x=49+-17 /16, x1=32/16=2, x2=66/16=33/8,
y1=9-3*2=3, y2=9-66/8=72-99 /8=-27/8, отв. (2;3) u (33/8; -27/8)
d) log(xy) 4=log4 4, xy=4, y=7+2x, x(7+2x)=4, 7x+2x^2=4,
2x^2+7x-4=0, D=81, x=-7+-9 /4, x1=-4, x2=1/2, y1=7-8=-1, y2=7+1=8
отв (-4;-1) u (1/2;8)