Question

If a+b = 4 and ab = -12 find (i) a-b and (ii) a^2-b^2

Answer 1

Answer:

click on the photo.....

Answer 2

Answer:

given, ab = -12

a = -12/b

a+b = 4

-12/b + b = 4

-12 + b^2/b=4

-12 + b^2 = 4b

b^2 -4b -12 = 0

b^2 -6b+2b-12=0

b(b- 6) +2(b - 6) = 0

(b+2) (b-6) = 0

b = -2,6

hence, positive value taken in any equation.

a+b =4

a+ 6 = 4

a = 4-6 = -2

now,

(i) a-b = -2 +6

= 4 ans.

(ii) a^2 - b^2 = a^2 + b^2 - 2ab

= (-2)^2 + (6)^2 - 2×(-12)

= 4 + 36 +24

= 66 ans.