Question

simplify 3x(4x-5)+3 and find its value for '1' x=3
'2'x=1by2​

Answer 1

Answer:

3x(4x-5) +3

=12x²-15x+3

if x=3 so....

12(3)² - 15.3 + 3

=12.9 - 45 + 3

=108 - 45 + 3

=111 - 45

=66

or,.... x=1/2

then,....

12.(1/2)² - 15.1/2 + 3

=12.1/4 - 15.1/2 + 3

= 3 - 15/2 + 3

= 9 - 15/2

=(18-15)/2

= 3/2

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