Question

b) 2(3x+7)<-4x+8 c) 20-(2x+5)_< 11 +8X

Answer 1

Explicação passo-a-passo:

$b) \: 2.(3x + 7) < - 4x + 8$

= 6x+14 < -4x+8 V = 6x+14 > -(-4x+8)

= 6x+4x < 8-14 V = 6x+14 > +4x-8

= 10x < -6 V = 6x-4x > -8-14

= x < -6/10 V = 2x > -22

= x < -3/5 V = x > -22/2

= x > -11

S.:[-11;-3/5]

$c) \: 20 - (2x + 5) \leqslant 11 + 8x$

= 20-2x-5 ≤ 11 + 8x V = 20-2x-5 ≥ -(11+8x)

= -2x-8x ≤ 11+5-20 V = 20-2x-5 ≥ -11-8x

= -10x ≤ 15-20 V = -2x+8x ≥ -11+5-20

= -10x ≤ -5 V = 6x ≥ -26

= (-1) -x ≤ -5/10 (÷5) V = x ≥ -26/6 -- (-2)

= x ≤ 1/2 V = x ≥ -13/3

S.: ]-∞;-13,3[U]1/2;+∞[