1. a)5 < m < 15; 5*1/5 < 1/5 m < 15*1/5; 1 < 1/5 < 3
b) 5 < -2m < 15; 5*(-2) < -2m < 15*(-2); -10 < -2m < -30; -30 < -2m < -10
c) 5 < m-6 < 15; -5+6 < m-6 < -15+6 ; 1 < m-6 < -9; -9< m-6 < 1
2. a) 2.6 <√7 <2.7; 2.6*2 < 2√7 < 2.7*2 ; 5.2 < √7 < 5.4
b)- 2.6 <-√7 < -2.7; -2,7 < -√7 < -2,6
c) 2.6 <√7 <2.7; 2+2.6 < 2+√7 < 2+2.7; 4.6 < √7 < 4.7
d)2.6 <√7 <2.7; 3-2.6 < 3-√7 <3-2.7; 0.4 <;3-√7 <0.3; 0.3 < 3-√7 < 0.4
16x^2-8x+1-4x+1-12=0
16x^2-12x-10=0
2(8x^2-6x-5)=0
2(8x^2+4x-10x-5)=0
2(4x*(2x+1)-5(2x+1))=0
2(4x-5)*(2x+1)=0
(4x-5)*(2x+1)=0
4x-5=0 x1=5/4
2x+1=0 x2=-(1/2)