Advertisements
Advertisements
प्रश्न
The area of a circle is given by the expression πx2 + 6πx + 9π. Find the radius of the circle.
Advertisements
उत्तर
We have,
Area of a circle = πx2 + 6πx + 9π = π(x2 + 6x + 9)
⇒ πr2 = π(x2 + 3x + 3x + 9) ...[∵ Area of a circle = πr2, where r is the radius]
⇒ πr2 = π[x(x + 3) + 3(x + 3)] = π(x + 3)(x + 3) = π(x + 3)2
⇒ πr2 = π(x + 3)2
On comapring both sides, r2 = (x + 3)2 ⇒ r = x + 3
Hence, the radius of circle is x + 3.
APPEARS IN
संबंधित प्रश्न
Use a suitable identity to get the following products.
(2y + 5) (2y + 5)
Find the following squares by suing the identities.
(b − 7)2
Simplify (2.5p − 1.5q)2 − (1.5p − 2.5q)2
Using a2 − b2 = (a + b) (a − b), find 512 − 492
Using a2 − b2 = (a + b) (a − b), find 12.12 − 7.92
Use the formula to multiply the following.
(3x − 5) (3x + 5)
Use the formula to multiply the following.
(a + 6) (a − 6)
Use the formula to find the value.
502 × 498
Factors of 9x2 + 6xy are
Factorise the following.
x2 + 9x + 20
