Question

If a + b = 10 and ab = 21, find the value of a’ + 63​

Answer 1

Answer:

Step-by-step explanation:

a+b=10

squaring both sides

a2+b2+2ab=100

a2+b2+2*21=100

a2+b2=100-42

a2+b2=58

Answer 2

EXPLANATION.

• GIVEN

a + b = 10

ab = 21

Find value of a + 63

a + b = 10 ....(1)

ab = 21 ....(2)

from equation (2) we get,

$\bold{a \: = \frac{21}{b}} .....(3)$

put the value of a = 21/b in equation (1)

we get,

$\bold{\frac{21}{b} + b \: = 10}$

$\bold{21 + {b}^{2} = 10b}$

$\bold {b}^{2} - 10b \: + 21 = 0$

$\bold{{b}^{2} - 7b \: - 3b \: + 21 = 0}$

$\bold b \: (b - 7) - 3(b - 7) = 0$

$\bold(b - 3)(b - 7) = 0$

$\bold{b \: = 3 \: \: and \: \: b \: = 7}$

put the value of b in equation (3)

we get,

Put b = 3 we get,

a = 21/b = 21/3 = 7

put b = 7

a = 21/b = 21/7 = 3

Therefore,

a = 7 and b = 3

a = 3 and b = 7

value of a + 63

put a = 7

7 + 63 = 70

put a = 3

3 + 63 = 66

Therefore,

a + 63 = 70 and 66