which of the following values of x make the equation has no real roots


[tex]a. {2x}^{2} + 4 \times = 3 [/tex]
[tex]b.t {}^{2} - 8t - 4 = 0[/tex]
[tex]c.3 {s}^{2} - 2s = - 5[/tex]
[tex]d. - 2 {r}^{2} + 7 = 0[/tex]


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