Решить уравнение:1) х²-7=0;2)3х²-7=0;3)-0,3у²+0,39=0;4)-у²+6=0;4)-4х²+19=0

[latex]x^2-7=0 \\\ x^2=7 \\\ x=\pm \sqrt{7} [/latex] [latex]3x^2-7=0 \\\ 3x^2=7 \\\ x^2= \frac{7}{3} \\\ x=\pm \sqrt{ \frac{7}{3} } [/latex] [latex]-0.3y^2+0.39=0 \\\ -0.3y^2=-0.39 \\\ y^2=1.3 \\\ y=\pm \sqrt{1.3} [/latex] [latex]-y^2+6=0 \\\ y^2=6 \\\ y=\pm \sqrt{6} [/latex] [latex]-4x^2+19=0 \\\ 4x^2=19 \\\ x^2=4.75 \\\ x=\pm \sqrt{4.75} [/latex]