Advertisements
Advertisements
प्रश्न
If a − b = 4 and ab = 21, find the value of a3 −b3
Advertisements
उत्तर
In the given problem, we have to find the value of `a^3 - b^3`
Given `a-b = -4,ab = 21`
We shall use the identity `(a-b)^3 = a^3- b^3 - 3ab(a-b)`
Here putting, a-b = - 4,ab = 21,
`(4)^3 = a^3 - b^3 - 3 (21) (4)`
`64 = a^3 - b^3 - 252`
`64 + 252 = a^3 -b^3`
`316 = a^3 - b^3`
Hence the value of `a^3 -b^3` is 316.
APPEARS IN
संबंधित प्रश्न
Evaluate following using identities:
991 ☓ 1009
Write in the expanded form:
`(a + 2b + c)^2`
Write the expanded form:
`(-3x + y + z)^2`
Write in the expanded form:
`(m + 2n - 5p)^2`
If a2 + b2 + c2 = 16 and ab + bc + ca = 10, find the value of a + b + c.
If a + b + c = 9 and ab + bc + ca = 23, find the value of a2 + b2 + c2.
If \[x^2 + \frac{1}{x^2}\], find the value of \[x^3 - \frac{1}{x^3}\]
Evaluate of the following:
1113 − 893
Find the following product:
\[\left( 3 + \frac{5}{x} \right) \left( 9 - \frac{15}{x} + \frac{25}{x^2} \right)\]
If a + b = 6 and ab = 20, find the value of a3 − b3
If a − b = 5 and ab = 12, find the value of a2 + b2
Mark the correct alternative in each of the following:
If \[x + \frac{1}{x} = 5\] then \[x^2 + \frac{1}{x^2} = \]
Use the direct method to evaluate :
(x+1) (x−1)
Evaluate: (9 − y) (7 + y)
If `x + (1)/x = 3`; find `x^2 + (1)/x^2`
If a2 - 3a - 1 = 0 and a ≠ 0, find : `"a" + (1)/"a"`
If a2 + b2 + c2 = 41 and a + b + c = 9; find ab + bc + ca.
If p2 + q2 + r2 = 82 and pq + qr + pr = 18; find p + q + r.
Simplify:
`("a" - 1/"a")^2 + ("a" + 1/"a")^2`
Simplify:
(x + y - z)2 + (x - y + z)2
