Advertisements
Advertisements
प्रश्न
If a - b = 7 and ab = 18; find a + b.
Advertisements
उत्तर
We know that,
( a - b )2 = a2 - 2ab + b2
and
( a + b )2 = a2 + 2ab + b2
Rewrite the above equation, we have
( a + b )2 = a2 + b2 - 2ab + 4ab
= ( a + b )2 + 4ab ...(1)
Given that a - b = 7; ab = 18
Substitute the values of ( a - b ) and (ab)
in equation (1), we have
( a + b )2 = (7)2 + 4(18)
= 49 + 72 = 121
⇒ a + b = `+- sqrt121`
⇒ a + b = `+-11`
APPEARS IN
संबंधित प्रश्न
Factorise:
4x2 + 9y2 + 16z2 + 12xy – 24yz – 16xz
Simplify the following:
0.76 x 0.76 - 2 x 0.76 x 0.24 x 0.24 + 0.24
Simplify the following products:
`(m + n/7)^3 (m - n/7)`
Simplify the following product:
(x2 + x − 2)(x2 − x + 2)
Simplify (a + b + c)2 + (a - b + c)2 + (a + b - c)2
If a + b + c = 9 and a2+ b2 + c2 =35, find the value of a3 + b3 + c3 −3abc
Mark the correct alternative in each of the following:
If \[x + \frac{1}{x} = 5\] then \[x^2 + \frac{1}{x^2} = \]
If a2 - 3a + 1 = 0, and a ≠ 0; find:
- `a + 1/a`
- `a^2 + 1/a^2`
Use the direct method to evaluate the following products:
(a – 8) (a + 2)
Use the direct method to evaluate :
(4+5x) (4−5x)
