1)
4x^2-(4x^2-4x+1)=15
4x^2-4x^2+4x-1=15
4x-1=15
4x=16
x=16/4
x=4;
2)
9x^2-1=9x^2-12x+4
9x^2-9x^2+12x=4+1
12x=5
x=5/12
3)
9x^2+6x+1-(9x^2-6x+1)=11x+1.2
9x^2+6x+1-9x^2+6x-1=11x+1.2
12x=11x+1.2
12x-11x=1.2
x=1.2
1)
4x^2-(4x^2-4x+1)=15
4x^2-4x^2+4x-1=15
4x-1=15
4x=16
x=16/4
x=4;
2)
9x^2-1=9x^2-12x+4
9x^2-9x^2+12x=4+1
12x=5
x=5/12
3)
9x^2+6x+1-(9x^2-6x+1)=11x+1.2
9x^2+6x+1-9x^2+6x-1=11x+1.2
12x=11x+1.2
12x-11x=1.2
x=1.2