Question

Q.8 of 9
If a + b = 9 and ab = 5. Find the value
of a2 + b2
(2 marks)​

Answer 1

Answer:

$(a + b) = {a}^{2} + {b}^{2} - 2ab$

$(a + b) + 2ab = {a}^{2} + {b}^{2}$

$given \: a + b \: = 9,</p><p>ab = 5$

${a}^{2} + {b}^{2} = (a + b) + 2ab$

${a}^{2} + {b}^{2} = (9) + 2 \times 5$

${a}^{2} + {b}^{2} = 9 + 10$

${a}^{2} + {b}^{2} = 19$

Answer 2

$\frac{5}{b}$Answer:

Given

a + b = 9

or,a = 9 - b.......eq-i

Now,

ab = 5

or, ( 9 - b ) X b = 5 (from eq-i)

or , 9b - $b^{2}$ = 5

or , 9b = 5 + $b^{2}$

or , $\sqrt{9b}$ = 5 + $b^{2}$

or ,$3\sqrt{b}$ = 5 + $b^{2}$

or , $\sqrt{b}$ = $\frac{5 + b^{2} }{3}$

or , b = $(\frac{5 + b^{2} }{3})^{2}$

or , b = 20 + $\frac{2b^{2} }{5}$

or , b - 20 = $\frac{2b^{2} }{5}$

or , 5 ( b - 20 ) = $2b^{2}$

or  ,$\frac{ 5b - 100}{2}$  =  $b^{2}$

Step-by-step explanation:

sorry I can't slove it . But I have tried