14) (2x-1)^2=49 15) (3x+6)^2=(2x+9)^2
<=>(2x-1)^2-49=0 <=> (3x+6)^2-(2x+9)^2=0
<=>(2x-1+7)(2x-1-7)=0 <=>(3x+6+2x+9)(3x+6-2x-9)=0
th1: 2x+6=0 th1: 5x+15=0
<=>x=-3 <=>x=-3
th2: 2x-8=0 th2: x-3=0
<=>x=4 <=>x=3
16) (3x+1)^2= (5+2x)^2 17) (1-7x)^2=(3x-2)^2
<=> (3x+1)^2-(5+2x)^2=0 <=>(1-7x)^2-(3x-2)^2=0
<=>(3x+1+5+2x)(3x+1-5-2x)=0 <=>(1-7x+3x-2)(1-7x-3x+2)=0
th1: 5x+6=0 th1: -4x-1=0
<=>x=-6/5 <=>x=-1/4
th2: x-4=0 th2: -10x+3=0
<=>x=4 <=>x=3/10
18)x^2-5x+6=0 19) x^2-3x+2=0
<=>x^2-3x-2x+6=0 <=> x^2-x-2x+2=0
<=>x(x-2)-3(x-2)=0 <=>x(x-1)-2(x-1)=0
<=>(x-2)(x-3)=0 <=>(x-1)(x-2)=0
th1: x-2=0 th1: x-1=0
<=>x=2 <=>x=1
th2: x-3=0 th2: x-2=0
<=>x=3 <=>x=2
20) x^2-4x+3=0
<=>x^2-x-3x+3=0
<=>x(x-1)-3(x-1)=0
<=>(x-1)(x-3)=0
th1: x-1=0
<=>x=1
th2: x-3=0
<=>x=3
