Question:
Mark (✓) against the correct answer:
12x2 + 60x + 75 = ?
(a) (2x + 5)(6x + 5)
(b) (3x + 5)2
(c) 3(2x + 5)2
(d) none of these
Solution:
(c) $3(2 x+5)^{2}$
$12 x^{2}+60 x+75$
$=3\left(4 x^{2}+20 x+25\right)$
$=3\left((2 x)^{2}+2 \times 2 x \times 5+5^{2}\right)$
$=3(2 x+5)^{2}$