Question

please answer....... I will mark the brainliest, question 6+7​

Answer 1

7)

$\frac{2 + 5 \sqrt{7} }{2 - 5 \sqrt{7} } \times \frac{2 + 5 \sqrt{7} }{2 + 5 \sqrt{7} } = a + b \sqrt{7} \\ \frac{(2+ \sqrt{7}) {}^{2} }{2 {}^{2} - (5 \sqrt{7 }) {}^{2} } = a + b \sqrt{7} \\ \frac{4 + 7 + 4 \sqrt{7} }{4 - 175} = a + b \sqrt{7} \\ \frac{11 + 4 \sqrt{7} }{ - 174} = a + b \sqrt{7}$

On comparison we get

a = 11 / – 174

b = 4 / – 174

Answer 2

Answer:

Step-by-step explanation:

6)

Let x =    14.12121212...

100x = 1412.121212..

99x =   1398

x = 1398/99

7)

(2+5√7)(2+5√7)/(2-5√7)(2+5√7)

(2+5√7)(2+5√7)/(4-175)

(4+175+20√7)/(-171)

(179+20√7)/(-171)

(-179/171) -(20/171)√7

a = (-179/171)

b = (-20/171)