Question

if 6x² -1= 4x, let's show that 36x² +1/x²= 28​

Answer 1

$6x { \\ }^{2} - 1 = 4x \\ \div x \\ \\ \frac{6x {}^{2} }{x} - \frac{1}{x} = 4 \\ \: \: \: \: \: \: \: \: \: \: \\ (6x - \frac{1}{x} {}) {}^{2} = {4} ^{2} \\ {36x }^{2} + \frac{1}{ {x}^{2} } - 2 \times 6x \times \frac{1}{x} = 16 \\ {36x}^{2} + \frac{1}{ {x}^{2} } - 2 \times 6 \times 1 = 16 \\ 36x {}^{2} + \frac{1}{x {}^{2} } - 12 = 16 \\ 36 {}^{2} + \frac{1}{x {}^{2} } = 16 + 12 \\ 36 {x}^{2} + \frac{1}{ {x}^{2} } = 16 + 12 \\ 36 {x}^{2} + \frac{1}{ {x}^{2} } = 28 \\ hence \: proved$