5x(2x +1) = 0 --> x = - 0.5
25 - 100x^2 = 25*(1 - 4x^2) = 25*(1 - 2x)(1+2x) --> x 1 = +0.5 x2 = - 0.5
25x^2 - 14 = 0; 25x^2 = 14 ; x^2 = 0.56 --> x = v 0.56
2x^2 - 8 = 0; 2x^2 = 8; x^2 = 4; x1= 2; x2 = -2
4x^2 - 12=0; 4x^2 = 12; x^2 = 3 ; x = v 3
x^2 - 10x = 0 ; x(x - 10) = 0--> x = 10
4x^2 + 20x = 0; 4x(x + 5)=0--> x = - 5
2x^2 + x = 0; x(x + 1) = 0 --> x = - 1
3x^2 - 27 = 0; 3(x^2 - 9)=0; 3(x-3)(x+3)=0--> x1 = 3; x2 = - 3
4x^2 + 20x = 0; 4x(x + 5) = 0; x = - 5
5x(2x +1) = 0 --> x = - 0.5
25 - 100x^2 = 25*(1 - 4x^2) = 25*(1 - 2x)(1+2x) --> x 1 = +0.5 x2 = - 0.5
25x^2 - 14 = 0; 25x^2 = 14 ; x^2 = 0.56 --> x = v 0.56
2x^2 - 8 = 0; 2x^2 = 8; x^2 = 4; x1= 2; x2 = -2
4x^2 - 12=0; 4x^2 = 12; x^2 = 3 ; x = v 3
x^2 - 10x = 0 ; x(x - 10) = 0--> x = 10
4x^2 + 20x = 0; 4x(x + 5)=0--> x = - 5
2x^2 + x = 0; x(x + 1) = 0 --> x = - 1
3x^2 - 27 = 0; 3(x^2 - 9)=0; 3(x-3)(x+3)=0--> x1 = 3; x2 = - 3
4x^2 + 20x = 0; 4x(x + 5) = 0; x = - 5
х+z/2=1
x-z=3
выражаем х через z,получилось:
3+z+0,5z=1 (1) (1)3+z+0,5z=1
x=3+z 3+1,5z=1
1,5z=-2
z=-2/1,5
z=-1,3
получили систему
x=3-1,3
z=-1,3
ответ:х=1,7 и z=-1,3.
Но лучше спроси у одноклассников.