x- the square root of 2x+1 =7. Whats x?
回答 (8)
2008-08-28 5:33 pm
✔ 最佳答案
x - √(2x + 1) = 7-√(2x + 1) = 7 - x
√(2x + 1) = x - 7
2x + 1 = (x - 7)^2
2x + 1 = (x - 7)(x - 7)
2x + 1 = x*x - 7*x - x*7 + 7*7
2x + 1 = x^2 - 7x - 7x + 49
x^2 - 14x - 2x + 49 - 1 = 0
x^2 - 16x + 48 = 0
x^2 - 4x - 12x + 48 = 0
(x^2 - 4x) - (12x - 48) = 0
x(x - 4) - 12(x - 4) = 0
(x - 4)(x - 12) = 0
x - 4 = 0
x = 4
x - 12 = 0
x = 12
∴ x = 4 , 12
2008-08-29 12:35 am
x-sqrt(2x+1)=7
x-7=sqrt(2x+1)
x^2-14x+49=2x+1
x^2-16x+48=0
x1,x2=(16+-sqrt(256-4*1*48))/2=
(16+-8)/2=12,4
we need to check the answers, because we added solutions by squaring.
only x=12 works in the original equation, and that's the correct answer.
x-7=sqrt(2x+1)
x^2-14x+49=2x+1
x^2-16x+48=0
x1,x2=(16+-sqrt(256-4*1*48))/2=
(16+-8)/2=12,4
we need to check the answers, because we added solutions by squaring.
only x=12 works in the original equation, and that's the correct answer.
2008-08-29 12:35 am
x-sq.rt of 2x+1=7
x=7+sq.rt of (2x+1)
x should be a number which when multiplied by 2 and added to 1 should give the square root
so x=12
substituing x with 12 in the equation, you get
x=7+sq rt of (2(12)+1)
x=7+ sq. rt (24+1)
x=7+sq.rt 25
x=7+5
x=12
12 is the only number that fits into the equation.
x=7+sq.rt of (2x+1)
x should be a number which when multiplied by 2 and added to 1 should give the square root
so x=12
substituing x with 12 in the equation, you get
x=7+sq rt of (2(12)+1)
x=7+ sq. rt (24+1)
x=7+sq.rt 25
x=7+5
x=12
12 is the only number that fits into the equation.
2008-08-29 12:30 am
when square root of 2x+1=7
square it 2x+1=49
transfer 1 to theother side
2x=49-1=48
therefore
x=24
square it 2x+1=49
transfer 1 to theother side
2x=49-1=48
therefore
x=24
2008-08-29 12:29 am
x=3
so whats the square root of 3.
so whats the square root of 3.
2008-08-29 12:27 am
2x+1 = (sqrt(2x-1))^2 = 7^2 = 49
2x = 48
x = 24
2x = 48
x = 24
2008-08-29 12:46 am
The only correct answers above belong to Ratel and Falcor84. Intellectual got very close but forgot to plug in the two outputs (4 & 12) to see which one worked in the equation.
The answer, as Ratel and Falcor84 show you, is x=12.
The answer, as Ratel and Falcor84 show you, is x=12.
2008-08-29 12:42 am
2x+1=7
-1 -1
________
2x=6
--- ---
2 2
x=3
answer is x=3
-1 -1
________
2x=6
--- ---
2 2
x=3
answer is x=3
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