Help with the value of polynomial?

Question

Find the value of the polynomail -x^2+10x-10, when x= -5

just to let you know that I am trying I have got
-(-5^2)+10x-10=
-(25)+(-50)-10=
25+50-10
25+50=75-10=65

I know that somewhere I am messing up can somone help me find where I am making the mistake.

the other problem that I am struggling on is
the poduct of two consecutive positive intergers is 288. Find the intergers.

so far I ahve got
x(x+2)=288
x^2+2x-288=0
this is where I get lost.

please help me!!
Thanks

Answer 1

It seems as if in line three of your first problem, your negative signs just disappear.

Shouldn't it be:
-25 - 50 - 10
-75 - 10
- 85

.....

For the second problem it says consecutive positive integers, nothing about them being even or odd, so you would add 1 not 2.

x^2 + x - 228 = 0, but this won't factor.

Back to the equaiton you had before:
x^2 + 2x - 228 = 0
(x - 16)(x - 18) = 0 (cheated a bit, I took the square root of 288 which is about 16.9 and tested 16 and 18)
x - 16 = 0 or x - 18 = 0
x = 16 or 18

Answer 2

You were right up to the 1st two steps
-(-5^2)+10x-10=
-(25)+(-50)-10=
-25 -50 -10 = -85

x(x+1) = 288
x^2+x -288 = 0
This equation has no answer that is a whole number.
So maybe you meant cosecutive even numbers. If so, then your equation is x^+2x-288=0
Now use quadratic formula:
x =[ -2 +/- sqrt(4-4(-288))]/2
x = (-2 +/- 34)/2
x = (-2 -34)2 = -18 which is rejected because you want a + #
x = (-2 +34)/2 = 16
x+ 2 = 18
Check 16*18 = 288

Answer 3

Your mistake is in the parenthisis you should have:
-(-5)^2+10(-5)-10
-25-50-10
-85

On the other one:
x(x+2)=288
x^2+2x-288=0
(x-16)(x+18)
X-16=0 or x+18=0
x=16 or x= -18

And in the case of this problem the answer is 16 and 18.

Answer 4

well for ur first problem ur mistake is where u have 25+50-10, it should be -25-50-10. because a positive times a negative is a negative, not positive. your answer would be -85.

the second problem uve have right so far, now u just gotta find what equals 2 numbers multiply to give u -288, and add up to be +2. what i got was that (x+18)(x-16). x would then equal -18 and +16

Answer 5

Error in going from second line to third. Don't change -25 and -50 to their positives - - I'm not sure what rule you thought you were using to do this, but it's not valid.

Should be -25 - 50 - 10 = -85

OK I see mirramai beat me to get these answered, so all I'll add is that these are integers not intergers.

Answer 6

-5^2=+25(negative times negative makes a postitve)(there's your problem)
-5*10=-50
25-50-10=-35

problem 2:use quadratic formula
-2 +or- sqareroot4+(1152)<--makes 34
-2+or-34, divided by 2

makes 16 or -18
16*18=288, answers are 16 and 18

Answer 7

i think the ftrst one is wrong u must take - sign common from whoke equation

and in second one u are making wrong equation

u must use x(x+1) as it is consecutive no.