f`(x)=3*(2x+1)+(3x+5)*2=6x+3+6x+10=12x+13
f`(3)=36+13=49
f(x)= 6x^2+3x+10x+5+40 = 6x^2+13x+45
f'(x)=6*2x+13=12x+13
f'(3)=12*3+13=36+13=49
f`(x)=3*(2x+1)+(3x+5)*2=6x+3+6x+10=12x+13
f`(3)=36+13=49
f(x)= 6x^2+3x+10x+5+40 = 6x^2+13x+45
f'(x)=6*2x+13=12x+13
f'(3)=12*3+13=36+13=49