Question

if (a-b) = 3, a b= 4 find 1.ab and A square - B square
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Answer 1

Answer:

Step-by-step explanation:

so 1/a²+1/b²=(a²+b²)/(ab)²

=((a+b)²-2ab)/(ab)²

now put the values

=((4)²-2(3))/(3)²

=10/9

Answer 2

Answer:

a² - b² = -15

Step-by-step explanation:

a - b = 3 --> a = b+3

ab = 4

by substitution method,

(b + 3) * b = 4

b² + 3b - 4 = 0

b² - b + 4b - 4 = 0

b ( b - 1 ) + 4 ( b - 1)= 0

( b - 1 ) ( b + 4 )

therefore b = 1 or b = -4

so a - b = 3

if b = 1,

a = 4

if b = - 4 ,

a = -1

ab = 4

a² - b² = (∓1)² - (∓4)²

= 1 - 16

= -15