X^4-9x^2+ 14 find the real-number solutions of the equation.

x^4-9x^2+ 14
=(x^2 - 7)(x^2 - 2)

solve for x
x^2-2 = 0 
x^2 = 2
x = +√ 2  = +  1.4142 and x = -√ 2  = -  1.4142

x^2-7 = 0 
x^2 = 7
x = + √ 7 = +2.6458 and x = - √ 7 = - 2.6458

4 solutions

x = +√ 2  = + 1.4142
x = - √ 2  = - 1.4142 
x = + √ 7 = +2.6458
x = -  √ 7 = - 2.6458