Question

1) 0.2*(5у-2)=0.3*(2у-1)-0.9 2) 1.2*(0.5-5х)+4.2=3*(4-2.1х) 3) 4.5-1.6*(5х-3)=1.2*(4х-1)-15.1

Answer 1

1) $0,2(5y-2)=0,3(2y-1)-0,9$

$y-0,4=0,6y-0,3-0,9$

$y-0,4=0,6y-1,2$

$y-0,6y=-1,2+0,4$

$0,4y=-0,8$

$y=-0,8:0,4$

$y=-2$

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$0,2\cdot(5\cdot(-2)-2)=0,3\cdot(2\cdot(-2)-1)-0,9$ (это проверка)

$0,2\cdot(-10-2)=0,3\cdot(-4-1)-0,9$

$0,2\cdot(-12)=0,3\cdot(-5)-0,9$

$-2,4=-1,5-0,9$

$-2,4=-2,4$

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2) $1,2(0,5-5x)+4,2=3(4-2,1x)$

$0,6-6x+4,2=12-6,3x$

$4,8-6x=12-6,3x$

$6,3x-6x=12-4,8$

$0,3x=7,2$

$x=7,2:0,3$

$x=24$

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$1,2\cdot(0,5-5\cdot24)+4,2=3\cdot(4-2,1\cdot24)$

$1,2\cdot(0,5-120)+4,2=3\cdot(4-50,4)$

$1,2\cdot(-119,5)+4,2=3\cdot(-46,4)$

$-143,4+4,2=-139,2$

$-139,2=-139,2$

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3) $4,5-1,6(5x-3)=1,2(4x-1)-15,1$

$4,5-8x+4,8=4,8x-1,2-15,1$

$9,3-8x=4,8x-16,3$

$4,8x+8x=9,3+16,3$

$12,8x=25,6$

$x=25,6:12,8$

$x=2$

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$4,5-1,6\cdot(5\cdot2-3)=1,2\cdot(4\cdot2-1)-15,1$

$4,5-1,6\cdot(10-3)=1,2\cdot(8-1)-15,1$

$4,5-1,6\cdot7=1,2\cdot7-15,1$

$4,5-11,2=8,4-15,1$

$-6,7=-6,7$