Advertisements
Advertisements
प्रश्न
If a + b + c = 11 and a2 + b2 + c2 = 81, find : ab + bc + ca.
Advertisements
उत्तर
Since (a + b + c)2 = a2 + b2 + c2 + 2 (ab + bc + ca)
∴ (11)2 = 81 + 2 (ab + bc + ca)
∴ 2(ab + bc + ca) = 121 − 81 = 40
ab + bc + ca = `40/2`
⇒ ab + bc + ca = 20
APPEARS IN
संबंधित प्रश्न
If a+b=5 and ab = 6, find a2 + b2
If a2 + b2 = 29 and ab = 10, find : a + b
If a2 + b2 = 29 and ab = 10, find : a − b
If a2 + b2= 10 and ab = 3; find : a – b
If `2"x"-1/(2"x")=4`, find : `4"x"^2+1/(4"x"^2)`
If `3"x"+1/(3"x")=3`, find : `9"x"^2+1/(9"x"^2)`
The sum of the squares of two numbers is 13 and their product is 6. Find:
(i) the sum of the two numbers.
(ii) the difference between them.
If a2 + b2 = 41 and ab = 4, find : a – b
If 3x – 4y = 5 and xy = 3, find : 27x3 – 64y3.
The difference between the two numbers is 5 and their products are 14. Find the difference between their cubes.
