Question

a. If a-b =7 & ab= 18 ; find a+b
(1) (atb) (ii) a²-b2​

Answer 1

Answer:

a-b = 7. -eqn no 1

ab = 18. eqn no 2

a=b+7. eqn no 3

eqn 1 in eqn 2

(b+7)*b=18

b2+7b-18=0

b2+9b-2b-18=0

b(b+9)-2(b+9)=0

(b-2)(b+9)=0

b=2

b=-9

putting b=2 in eqn 3. putting b=-9 in eqn 3

a=b+7. a=b+7

a=2+7. a=-9+7

a=9. a=-2

a+b=9+2. a+b=-2+(-9)

=11. =-11

a2-b2=9*9-2*2. a2-b2=(-2*-2)-(-9*-9)

=81-4. =4-81

= 77. =-77