Question

Which of the following options gives all the real roots of the equation $x^4-11x^2+28=0$?

• A. $-\surd 7\text{and}\surd 7$
• B. $2\text{and}\surd 7$
• C. $-4,-\surd 7,\sqrt{7}\text{and}4$
• D. $-\surd 7,-2,2\text{and}\sqrt{7}$

Answer 1

The correct option is D $-\surd 7,-2,2\text{and}\sqrt{7}$