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i cant figure this out someone please help me. i am studying for a algebra 2 final and its on monday! please help!

2007-06-15 08:56:15 · 11 answers · asked by Joann f 1 in Science & Mathematics Mathematics

11 answers

Solve for "x"...

x^2 - 18x + 81 = 0

First: multiply the 1st & 3rd term to get 81. find two numbers that give you 81 when multiplied & -18 (2nd term) when added/subtracted. the numbers are (-9 & -9). rewrite the expression with the new middle terms.

x^2 - 9x - 9x + 81 = 0

Sec: group "like" terms; factor both sets of parenthesis.

(x^2 - 9x) - (9x + 81) = 0
x(x-9) - 9(x-1) = 0
(x-9)(x-9) = 0
(x-9)^2 = 0

Third: eliminate the exponent - find the square root of both sides.

V`(x-9)^2 = V`0
x - 9 = 0 (add 9 to both sides - when you move a term to the opposite side, always use the opposite sign).

x - 9+9 = 0+9
x = 9

2007-06-15 12:06:49 · answer #1 · answered by ♪♥Annie♥♪ 6 · 0 0

x^2 - 18x +81 = 0
(x-9)(x-9) = 0
Therefore, x = 9

2007-06-15 09:00:49 · answer #2 · answered by Werts 1 · 0 0

As written: x² = -80 one ?x² =?(-80 one) = ?80 one* ?(-a million) bear in mind ?(-a million) = i x= ±9i yet once you meant: x² + 18x = -80 one x² + 18x + 80 one =0 (x + 9)² = 0 x - 9 = 0 x = 9 it particularly is a double root(answer)

2016-11-24 22:22:44 · answer #3 · answered by thorpe 4 · 0 0

x² - 18x + 81 = 0
(x - 9).(x - 9) = 0
x = 9 (twice)

2007-06-16 03:45:27 · answer #4 · answered by Como 7 · 0 0

x^(2)-18x+81=0
(x-9) * (x-9) = 0

x = 9

2007-06-15 08:59:24 · answer #5 · answered by atheistforthebirthofjesus 6 · 0 0

x^(2) -18x+81=0
(x -9)*(x-9) = 0
x = 9 (double root)

2007-06-15 08:59:36 · answer #6 · answered by mark r 4 · 0 0

two numbers that multiply to 81 and add to -18

the two numbers are -9 and -9

(x - 9) (x - 9) = 0 or (x-9)^2 = 0
x = 9

2007-06-15 09:04:17 · answer #7 · answered by      7 · 0 0

x^2 - 18x + 81 = (x - 9)^2, so now it's boringly simple to find out the root..
Regards
Tonio

2007-06-15 08:59:16 · answer #8 · answered by Bertrando 4 · 0 1

factor into (x-9)(x-9)=0, a number times 0 equals 0 so you know that x-9=0, and x equals 9.

2007-06-15 09:00:59 · answer #9 · answered by Joe 2 · 0 1

its a quadratic equation so use the quatratic equation, u should of learn or easily find on line

2007-06-15 08:59:34 · answer #10 · answered by Anonymous · 0 1

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