Maths completing square pt3 help plz

Watch
Announcements
Thread starter 1 year ago
#1
Hey,

The question is y=4-7x-2x^2
I got up to -2(x-7/4)^2-49/8+4=0
After simplifying this, I don't get the answer given in the maths textbook.

I got -2(x-7/4)^2-17/8=0 then *-2
-2(x-7/4)^2+17/4=0

Which I said the turning point would be (7/4, 17/4). This is incorrect.

The actual turning point given in the textbook is (-7/4, 81/8)

What am I missing?
0
1 year ago
#2
You didn’t take into account when you divided -7x by -2.
0
Thread starter 1 year ago
#3
(Original post by Student 999)
You didn’t take into account when you divided -7x by -2.
Didn't I? I did it again and now got (-7/4, -17/8)
Still not got the full turning point
0
1 year ago
#4
+49/8, not minus
1
1 year ago
#5
y=4-7x-2x^2 = -2(x^2 + 7/2x) + 4 = -2[ (x + 7/4) - 49/16 ] + 4 ...
Try now...
1
Thread starter 1 year ago
#6
(Original post by vc94)
y=4-7x-2x^2 = -2(x^2 + 7/2x) + 4 = -2[ (x + 7/4) - 49/16 ] + 4 ...
Try now...
Thank you! Got the answer now
0
Thread starter 1 year ago
#7
(Original post by mqb2766)
+49/8, not minus
Thanks
0
X

new posts
Back
to top
Latest
My Feed

Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Poll

Join the discussion

Do you think receiving Teacher Assessed Grades will impact your future?

I'm worried it will negatively impact me getting into university/college (159)
44.41%
I'm worried that I’m not academically prepared for the next stage in my educational journey (40)
11.17%
I'm worried it will impact my future career (29)
8.1%
I'm worried that my grades will be seen as ‘lesser’ because I didn’t take exams (75)
20.95%
I don’t think that receiving these grades will impact my future (34)
9.5%
I think that receiving these grades will affect me in another way (let us know in the discussion!) (21)
5.87%