Step 1 :\( x_{1} = \sqrt{64} \), \( x_{2} = -\sqrt{64} \)
Step 2 :No real solution
Step 3 :\( x_{1} = \sqrt{108} \), \( x_{2} = -\sqrt{108} \)
Step 4 :\( x_{1} = \sqrt{200} \), \( x_{2} = -\sqrt{200} \)
Step 5 :\( \frac{4 x^{2}}{4} = \frac{81}{4} \), \( x_{1} = \sqrt{\frac{81}{4}} \), \( x_{2} = -\sqrt{\frac{81}{4}} \)
Step 6 :\( \frac{-3 x^{2}}{-3} = \frac{-54}{-3} \), \( x_{1} = \sqrt{18} \), \( x_{2} = -\sqrt{18} \)
Step 7 :\( \frac{-7 x^{2}}{-7} = \frac{49}{-7} \), \( x_{1} = \sqrt{7} \), \( x_{2} = -\sqrt{7} \)
Step 8 :\( 5 x^{2} = 400 \), \( x_{1} = \sqrt{80} \), \( x_{2} = -\sqrt{80} \)
Step 9 :\( 2 x^{2} = 14 \), \( \frac{2 x^{2}}{2} = \frac{14}{2} \), \( x_{1} = \sqrt{7} \), \( x_{2} = -\sqrt{7} \)
Step 10 :\( -3 x^{2} = -100 \), \( \frac{-3 x^{2}}{-3} = \frac{-100}{-3} \), \( x_{1} = \sqrt{\frac{100}{3}} \), \( x_{2} = -\sqrt{\frac{100}{3}} \)
Step 11 :\( \frac{1}{2} x^{2} = 40 \), \( x_{1} = \sqrt{80} \), \( x_{2} = -\sqrt{80} \)
Step 12 :\( 3 x^{2} = -150 \), \( \frac{3 x^{2}}{3} = \frac{-150}{3} \), \( x_{1} = \sqrt{50}i \), \( x_{2} = -\sqrt{50}i \)
Step 13 :For \( a x^{2}=c \), \( x_{1} = \sqrt{\frac{c}{a}} \), \( x_{2} = -\sqrt{\frac{c}{a}} \); For \( a x^{2}+b=c \), first isolate \( a x^{2} \) by subtracting \( b \) from both sides, then apply the same method.
Step 14 :\( r^{2} = \frac{160 \pi}{8 \pi} \), \( r = \sqrt{20} \), as a decimal \( r \approx 4.5 \)