Question

answer this please ~~ thank you​

Answer 1

We know (a-b)²=a²+b²-2ab

$(a - \frac{1}{a} ) {}^{2} = {a}^{2} + \frac{1}{a} {}^{2} - 2 \times a \times \frac{1}{a} \\ \\ ( a - \frac{1}{a} ) {}^{2} = 786 - 2 \\ \\ (a - \frac{1}{a} ) {}^{2} = 784 \\ \\ a - \frac{1}{a} = \sqrt{784} \\ \\ a - \frac{1}{a} = 28$

Answer 2

★GOOD MORNING★

Let a - 1/a = y

SQUARING BOTH SIDE'S WE HAVE

( a - 1/a )² = y ²

=>

a² + 1/a² - 2 = y²

=>

y² = 786 - 2

=>

y² = 784

=>

y = ±28

=>

a - 1/a = ±28

☺️☺️