Advertisements
Advertisements
प्रश्न
If a − b = −8 and ab = −12, then a3 − b3 =
पर्याय
−244
−240
−224
−260
Advertisements
उत्तर
To find the value of a3 − b3
Given `a-b = -8,ab =-12`
Using identity `(a-b)^3 = a^3 - b^3 -3ab(a-b)`
Here `a-b = -8,ab =-12`we get
`(-8)^3 = a^3 -b^3 -3ab(a-b)`
`(-8)^3 =a^3 -b^3 -3 xx -12 xx -8`
`-512 = a^3 -b^3 - 288`
Transposing -288 to left hand side we get
`- 512 + 288 = a^3 - b^3`
`-224 = a^3 - b^3`
Hence the value of `a^3 -b^3 `is -224 .
APPEARS IN
संबंधित प्रश्न
Factorise the following using appropriate identity:
4y2 – 4y + 1
Write the following cube in expanded form:
(2x + 1)3
Evaluate the following using suitable identity:
(998)3
Factorise the following:
27y3 + 125z3
Factorise the following:
64m3 – 343n3
Evaluate the following using identities:
`(a^2b - b^2a)^2`
Simplify the following:
0.76 x 0.76 - 2 x 0.76 x 0.24 x 0.24 + 0.24
If `x + 1/x = sqrt5`, find the value of `x^2 + 1/x^2` and `x^4 + 1/x^4`
Simplify the expression:
`(x + y + z)^2 + (x + y/2 + 2/3)^2 - (x/2 + y/3 + z/4)^2`
Find the cube of the following binomials expression :
\[\frac{3}{x} - \frac{2}{x^2}\]
If `x^4 + 1/x^4 = 194, "find" x^3 + 1/x^3`
If x = 3 and y = − 1, find the values of the following using in identify:
\[\left( \frac{5}{x} + 5x \right)\] \[\left( \frac{25}{x^2} - 25 + 25 x^2 \right)\]
Evaluate:
483 − 303 − 183
Use identities to evaluate : (502)2
Use the direct method to evaluate :
(xy+4) (xy−4)
Evaluate: 203 × 197
Evaluate, using (a + b)(a - b)= a2 - b2.
4.9 x 5.1
If p2 + q2 + r2 = 82 and pq + qr + pr = 18; find p + q + r.
If `"r" - (1)/"r" = 4`; find : `"r"^4 + (1)/"r"^4`
If a + b + c = 0, then a3 + b3 + c3 is equal to ______.
