Question

Simplify 3x(4x-5)+3 and find its values for
(i) x=3
(ii) x=^1/₂

Answer 1

3x(4x-5)+3 = 12x^2-15x+3
= 12x^2-12x-3x+3
= 12x(x-1)-3(x-1)
= (12x-3)(x-1)
= 3(4x-1)(x-1)
So, the simplified equation is : 3(4x-1)(x-1)
For x=3, the equation evaluates to 3(4(3)-1)(3-1) = 3(12-1)(2) = 3(11)(2) = 66
For x=1/2, the equation evaluates to 3(4(1/2)-1)((1/2)-1) = 3(2-1)(-1/2) = 3(1)(-1/2)= -3/2