Advertisements
Advertisements
प्रश्न
If a + b = 6 and ab = 20, 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 = ,ab = 20`
We shall use the identity
`a^3 -b^3 = (a-b)^3 3ab (a-b)`
`a^3 -b^3 = (a-b)^3 + 3ab(a-b)`
`a^3 - b^3 = (6)^3 3 xx 20(6)`
`a^3 - b^3 = 216 +360`
`a^3 -b^3 = 576`
Hence the value of `a^3 - b^3`is 576.
APPEARS IN
संबंधित प्रश्न
Expand the following, using suitable identity:
(x + 2y + 4z)2
What are the possible expressions for the dimensions of the cuboids whose volume is given below?
| Volume : 12ky2 + 8ky – 20k |
Write in the expanded form: (ab + bc + ca)2
Evaluate of the following:
(9.9)3
Find the value of 64x3 − 125z3, if 4x − 5z = 16 and xz = 12.
Find the following product:
\[\left( \frac{3}{x} - \frac{5}{y} \right) \left( \frac{9}{x^2} + \frac{25}{y^2} + \frac{15}{xy} \right)\]
If x + \[\frac{1}{x}\] = then find the value of \[x^2 + \frac{1}{x^2}\].
If \[x + \frac{1}{x} = 3\] then \[x^6 + \frac{1}{x^6}\] =
If \[\frac{a}{b} + \frac{b}{a} = - 1\] then a3 − b3 =
If a − b = −8 and ab = −12, then a3 − b3 =
If a + b = 7 and ab = 10; find a - b.
Use the direct method to evaluate the following products :
(y + 5)(y – 3)
Expand the following:
(a + 3b)2
Expand the following:
`(2"a" + 1/(2"a"))^2`
Find the squares of the following:
3p - 4q2
Evaluate, using (a + b)(a - b)= a2 - b2.
4.9 x 5.1
If a2 - 3a - 1 = 0 and a ≠ 0, find : `"a" - (1)/"a"`
If x + y + z = p and xy + yz + zx = q; find x2 + y2 + z2.
If `"r" - (1)/"r" = 4`; find: `"r"^2 + (1)/"r"^2`
