Question

Simplify 3x(4x-5)+3 find its value when i;x=3 ii; x=-4

Answer 1

Answer:

3x(4x-5)+3

=12x²-15x+3

if... (i) x=3... so

12.(3)²-15.3+3

=12.9-45+3

=108-45+3

=111-45

=66

or....(ii) x=-4

12(-4)²-15.(-4) +3

=12×16+60+3

=192+60+3

=255

Answer 2

:

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-- :

3x(4x−5)+3=12x^2−15x+3

x=3 gives the value 12(9)−15×3+3

                             =108−45+3

                              =66

x=1/2 gives the value 12(1/4)−15×(1/2)+3

                             =3−7.5+3

                              = - 3/2