Question

need help

Answer 1

yep?

Answer 2

Write the quadratic function in vertex form. (1 point)

y = x2 + 4x + 7

y = (x + 2)2 + 3
y = (x + 2)2 - 3
y = (x - 2)2 - 3
y = (x - 2)2 + 3

Answer 3

@LichKing

Answer 4

first write x^2 + 4x in the form ( x + a)^2 - b
a is found by dividing +4 ( from the 4x) by 2

Answer 5

so its ( x + 2)^2 - b

now if you expand (x +2)^2 you can see what you have to make b in order to get back to x^2 + 4x

Answer 6

can you work out what (x+2)^2 is - using the distributive law ?

Answer 7

no

Answer 8

you multiply x+2 by x then by 2 and simplify
(x + 2)^2 = (x + 2)(x + 2) = x(x+2) + 2(x+2)
=x^2 + 2x + 2x + 2
= x^2 +4x + 4

Answer 9

do you understand that?

Answer 10

yeah

Answer 11

so the answer is y = (x + 2)2 - 3 ?

Answer 12

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Answer 13

no - you have to find an expression which is equivalent to x^2 + 4x - what have you got to do to x^2 + 4x + 4 to make it same as x^2 + 4x ?

Answer 14

i have no idea.......

Answer 15

x^2 + 4x + 4 - b = x^2 + 4x

what must b be?

Answer 16

sorry - i might have confused you here - all we are doing at this stage is finding the equivalent of x^2 + 4x at this stage , We are dealing with the + 7 afterwards

Answer 17

b has to be 4
so x^2 + 4x = (x + 2)^2 - 4

Answer 18

now add the 7

to give (x + 2)^2 -4 + 7

= (x+2)^2 + 3

Answer 19

your answer was correct

Answer 20

if you would prefer to remember a formula to do these its

x^2 + bx + c = ( x + (b/2))^2 - (b/2)^2 + c

Answer 21

no you said in the answer -3 its +3