Question

Q3. A + B = 0 and AB = - 36.
What is the value of A-B?

Answer 1

A - B = ± 12

Explanation:

Given

A + B = 0 → (1)

AB = - 36 → (2)

Subtract B from both sides of (1)

A = - B ← substitute into (2)

- B(B) = - 36 ( multiply both sides by 0 1 )

B² = 36 ( take square root of both sides )

B = ± 6

Substitute into (1)

If B = 6 then A =- 6 and A-B = - 6 - 6 = - 12

If B = - 6 then A = 6 and A - B = 6 - (- 6) = 6 + 6 = 12

Answer 2

Explanation:

A + B = 0

A = -B

(-B)B) = -36

-B^2 = -36

B^2 = 36

B = 6, -6

So, A = -6, 6

A - B = -12

or

A - B = 12