-66.
4x2 + 12x + 5 = (2x + 1)(2x + 5).
4x2 - 2x = 0
4x2-11x-20=(x-4)(4x+5) 4x2-11x-20=4x2+ax+bx-20ab = 4*-20 = -80a+b = -11a = -16, b = 54x2-11x-20=4x2-16x+5x-204x2-16x+5x-20=4x(x-4)+5(x-4)4x(x-4)+5(x-4)=(x-4)(4x+5)Factorised, 4x2-11x-20=(x-4)(4x+5)
4x2 - 12x + 9 = 5; whence, 2x - 3 = ±√5, and 2x = 3 ±√5. Therefore, x = ½ (3 ±√5).
4x2+20x+25 (2x+5)^2
(2x - 5)(2x + 5)
4x2 + 12x + 5 = 4x2 + 2x + 10x + 5 = 2x(2x+1) + 5(2x+1) = (2x+1)(2x+5)
The first equality is: x2 - 5 = -4x2 which gives 5x2 - 5 = 0 which is equivalent to x2 - 5 = 0 The second equality is: -4x2 = 3x which gives 4x2 + 3x = 0 The two results are inconsistent.
c = 25 4x2 + 20x + 25 (2x + 5)(2x + 5)
(2x - 1)(2x + 5)
(2x - 5)(2x - 5)
(2x+5)(2x+5)