math help right quick

[RandyJ 10+ year member]

My girl was asking for some help in Alg II and so I decided to help. I helped her with the work but she said when she got to school the teacher said it was wrong. Been so long since Ive taken the course I cant remember. Someone help me here...

Evaluate H(X^2) when H(X)=10-2X

X^2=(X)(X)

=10-2X(10-2X)

= 100-20X-20X+4X^2

=100-40X+4X^2

Sub 2 for answer check

10-(2*2)=6

6*6=36

100-40(2)+4(2^2)

=100-80+16

=36

Im assuming I went wrong when I squared the initial function, anyone got anything to say?

Click to read more...

 

[cappy72 10+ year member]

it should be like this:

Evaluate H(X^2) when H(X)=10-2X

so ...

H(x^2) = 10 - 2(x^2)

= 10 - 2x^2

 

[Damaso87 10+ year member]

it should be like this:
Evaluate H(X^2) when H(X)=10-2X

so ...

H(x^2) = 10 - 2(x^2)

= 10 - 2x^2

lol, did you even take alg 2? you didnt multiply correctly...

You have it correct so far, you jsut didnt finish, solve for X by setting it equal to zero:

4x^2-40x+100=0

(2x-10)(2x-10)=0

pick one and set it equal to zero

2x-10=0

2x=10

x=5

check:

4(5)^2-40(5)+100=0

4(25)-200+100=0

100-200+100=0

0=0

voila.

 

[cappy72 10+ year member]

actually I completed calc 3...

I thought it was a simple substitution for X... since it doesnt say solve for x just evaluate it

 

[sumone 10+ year member]

^ I'm with him

if all the problem says is: "Evaluate H(X^2) when H(X)=10-2X", then the answer is 10-2x^2...

 

[Diplexers 10+ year member]

soo....... if 2+3=5...what is the value of 2???//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[slipitysmooth 10+ year member]

^ I'm with him
if all the problem says is: "Evaluate H(X^2) when H(X)=10-2X", then the answer is 10-2x^2...

yes..if it was "evaluate H(x)^2" then you would do what the other guy says...

 

[cappy72 10+ year member]

soo....... if 2+3=5...what is the value of 2???//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

no to me its more like h(2) = 10 - 2(2)

then you would say h(2) = 6

but because x is an unknown variable you need an equation to represent the possible values for h(x) hence 10- 2x^2...