Advertisements
Advertisements
प्रश्न
If a – b = 3 and ab = 10, find : a3 – b3.
Advertisements
उत्तर
a − b = 3
⇒ (a − b)3 = (3)3
⇒ a3 − b3 − 3ab (a − b) = 27
⇒ a3 − b3 − 3×10 (3) = 27
⇒ a3 − b3 − 90 = 27
⇒ a3 − b3 = 27 + 90
⇒ a3 − b3 = 117
Alternative Method :
(a − b)3 = a3 − b3 − 3ab (a − b)
⇒ (3)3 = a3 − b3 − 3×10 (3)
⇒ 27 = a3 − b3 − 90
⇒ 27 + 90 = a3 − b3
⇒ 117 = a3 − b3
⇒ a3 − b3 = 117
APPEARS IN
संबंधित प्रश्न
If a2 + b2= 10 and ab = 3; find : a – b
If `"a"^2+ 1/"a"^2=23`, find : `"a" +1/"a"`
If `"a"^2+ 1/"a"^2=11`, find : `"a" -1/"a"`
If a + b = 6 and ab = 8, find: a3 + b3.
If `2"x"-1/(2"x")=4`, find: `8"x"^3-1/(8"x"^3)`
If `3"x"+1/(3"x")=3`, find : `27"x"^3+1/(27"x"^3)`
If a + b + c = 11 and a2 + b2 + c2 = 81, find : ab + bc + ca.
If 3x – 4y = 5 and xy = 3, find : 27x3 – 64y3.
If a + b = 8 and ab = 15, find a3 + b3.
If 3x + 2y = 9 and xy = 3, find : 27x3 + 8y3.
