Question 4(a)
Simplify : 3x (4x-5) +3 and find values for (i) x=3 (ii) x= 12
3x(4x−5)+3=3x×4x−3x×5+3=12x2−15x+3
(i) For x=3,
12x2+15x+3=12(3)2−15×3+3
=12×9−45+3=108−45+3=66
(ii) For x=12
12x2−15x+3=12×(12)2−15×12+3=12×14−152+3
=6−152=12−152=−32