Answer: 9x^2-9x-10 ==> D
Step-by-step explanation:
(3x+2)(3x-5)=
3x*3x + (-5)(3x) + 2*3x + (-5)(2)=
9x^2 - 5(3x) + 6x - 5(2)=
9x^2-15x+6x-10=
9x^2-15x+6x-10= 9x^2-9x-10 ==> D
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Explanation:
Let's make
y = 3x+2
So we can replace the (3x+2) with y
We go from (3x+2)(3x-5) to y(3x-5)
Distribute that y term through
y(3x-5)
y(3x) + y(-5)
3xy - 5y
Then plug in y = 3x+2 and distribute two more times
3xy - 5y
3x( y ) - 5( y )
3x( 3x+2 ) - 5( 3x+2 )
3x(3x) + 3x(2) - 5(3x) - 5(2)
9x^2 + 6x - 15x - 10
9x^2 - 9x - 10
which seems to point to choice D assuming the -9 in the middle is supposed to be -9x
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Side note: Alternative methods are the FOIL rule and the box method.