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(x+8)^2=81

Thank you so much

2007-12-26 04:17:38 · 10 answers · asked by CollegeYearRound 1 in Science & Mathematics Mathematics

10 answers

sqrt(x+8)^2 = sqrt(81)
x+8 =9
x=1

2007-12-26 04:22:19 · answer #1 · answered by WhatWasThatNameAgain? 5 · 0 1

x+8)² = 81

If we notice|fix (x+8)², of a remarkable product or also enumenat remarkable formula, which he|she|it says: The square of the sum of two numbers him equal to|in the square of the first, more the double of
frequents the first for the second, more the square of the second.


Therefore:

x² + 2x(8) + 8² = 81

x² + 16x +64 = 81

x² + 16x + 64 - 81= 0

x² + 16x - 17= 0

This qu once solved by the usual procedure is a quadratic equation,
it faces|gives:

x' = 1

x" = -17

Greetings from Catalonia and until the next one


Good Christmas

2007-12-26 11:24:13 · answer #2 · answered by josep d 7 · 1 0

(x+8)² = 81
x + 8 = √81
x + 8 = ±9

Remember for a quadratic equation there are two roots, since the square root of 81 is positive or negative 9 you have two real solutions.

x = -9 -8 = -17
x = 9 -8 = 1

2007-12-26 04:26:50 · answer #3 · answered by Brian K² 6 · 1 0

Step one: Take the square root of both sides. You will get:
x+8=9 OR x+8=-9, because 9^2 is 81, and so is (-9)^2.
Step two: Subtract 8 from both sides.

You get x=1 or x=-17


Hope I helped!!

:o)

2007-12-26 04:28:03 · answer #4 · answered by :o) Sunshine 3 · 1 1

x + 8 = ± 9
x = 1 , x = - 17

2007-12-29 19:53:39 · answer #5 · answered by Como 7 · 2 0

(x + 8)^2 = 81
x + 8 = √81
x + 8 = 9
x = 9 - 8
x = 1

2007-12-26 04:23:07 · answer #6 · answered by An ESL Learner 7 · 0 1

x^2+2*x*8+64=81
x^2+16*x=17
x^2+16*x-17=0


D=b^2-4*a*g
=256-4*1*(-17)
=256-68
=188>0

X 1,2= -b + / - D
= -16 + / - (root of number 188)

2007-12-26 04:34:55 · answer #7 · answered by P Defere 1 · 0 1

(x+8)^2 = 81

taking sq rt from both side

x+8 = 9 or x+8 = -9

x = 1 or x = -17

2007-12-26 04:25:24 · answer #8 · answered by jaya 4 · 1 1

(x+8)*2=9*2
x=1

2007-12-26 05:48:06 · answer #9 · answered by praman18 2 · 0 0

x^2+16x+64=81
x^2+16x-17=0
x^2+17x-x-17=0
x(x+17)-1(x+17)=0
(x+17)(x-1)=0
x=1 or x=-17

2007-12-26 04:27:48 · answer #10 · answered by cidyah 7 · 2 1

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