Question

7(3-4b)-5(3b+4),если b=-0,2;-2(3,1х-1)+3(1,2х+1)-8(0,3х+3),если х=0,8(расписать)

Answer 1

7( 3 - 4b ) - 5( 3b + 4 ) = 21 - 28b - 15b - 20 = 1 - 43b
b = - 0,2 
1 - 43 * ( - 0,2 ) = 1 + 8,6 = 9,6 
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- 2( 3,1x - 1 ) + 3( 1,2x + 1 ) - 8( 0,3x + 3 ) = - 6,2x + 2 + 3,6x + 3 - 2,4x - 24 =
= - 5x - 19 
x = 0,8 
- 5 * 0,8 - 19 = - 4 - 19 = - 23