Question

If a+b =20 and a – b=5, then the value of 4ab is__​

Answer 1

Answer:

a = 12.5 and b = 7.5

Step-by-step explanation:

12.5 - 7.5 = 5

12.5 + 7.5 = 20

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Answer 2

Answer:

4ab = 375

Step-by-step explanation:

a + b = 20 -------- i

a - b = 5 ---------- ii

Adding i & ii,

2a = 25

a = 25/2

Putting value of a = 25/2 in eq. i

25/2 + b = 20

b = 20-25/2 = (40-25)/2 = 15/2

Therefore ,

4ab = 4× 25/2 × 15/2

= 25×15

= 375