reign8162
reign8162 reign8162
  • 23-06-2021
  • Mathematics
contestada

If a + b = 2 and a - b = -4 what is the value of ab A. 5 B. -5 c.3 D. -3​

Respuesta :

jimrgrant1 jimrgrant1
  • 23-06-2021

Answer:

D

Step-by-step explanation:

Given the 2 equations

a + b = 2 → (1)

a - b = - 4 → (2)

Add the equations term by term to eliminate b

2a + 0 = - 2

2a = - 2 ( divide both sides by 2 )

a = - 1

Substitute a = - 1 into (1) and solve for b

- 1 + b = 2 ( add 1 to both sides )

b = 3

Then

ab = - 1 × 3 = - 3 → D

Answer Link
Dalewillow
Dalewillow Dalewillow
  • 23-06-2021

Answer:

option d

Step-by-step explanation:

a+b=2. ,. a-b = -4

a= 2-b

substituting values, we get

(2-b) - b = -4

2 -b -b =-4

2 -2b =-4

-2b = -4-2

2b= 6

b =3

a = 2-3

a= -1

ab = 3×-1

ab = -3

Answer Link

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