Hi all,
I hope this is the right place for this post.
I am trying to learn evaluating functions but I am stuck.
Given f (x) = 2x2 + 4x - 3, find f (2a + 3).
f (2a + 3) = 2(2a + 3)2 + 4(2a + 3) - 3
= 2(4a2 + 12a + 9) + 8a + 12 - 3
= 8a2 + 24a + 18 + 8a + 12 - 3
= 8a2 + 32a + 27
My problem comes at second row.
Could someone explain how do you get = 2(4a2 + 12a + 9) where does 12a come from ?
For me 2(2a + 3)2 = 2(4a+9) = 8a + 18
or when I multiply the brackets first before power I get 2(2a + 3)2 = (4a + 6)2 = 16a +36
What am I missing ?
Thank you
I hope this is the right place for this post.
I am trying to learn evaluating functions but I am stuck.
Given f (x) = 2x2 + 4x - 3, find f (2a + 3).
f (2a + 3) = 2(2a + 3)2 + 4(2a + 3) - 3
= 2(4a2 + 12a + 9) + 8a + 12 - 3
= 8a2 + 24a + 18 + 8a + 12 - 3
= 8a2 + 32a + 27
My problem comes at second row.
Could someone explain how do you get = 2(4a2 + 12a + 9) where does 12a come from ?
For me 2(2a + 3)2 = 2(4a+9) = 8a + 18
or when I multiply the brackets first before power I get 2(2a + 3)2 = (4a + 6)2 = 16a +36
What am I missing ?
Thank you
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