Asked by Kristi
square root>(3x + 1)− square root>(7x + 8)= 1
Answers
Answered by
Reiny
√(3x+1) - √(7x+8) = 1 , clearly x≥-1/3
√(3x+1) = 1 + √(7x+8)
square both sides
3x+1 = 1 + 2√(7x+8) + 7x+8
-4x -8 = 2√(7x+8)
-2x-4 = √7x+8)
square both sides again
4x^2 + 16x + 16 = 7x+8
4x^2 + 9x + 8 = 0
x = (-9 ± √-47)/8
no real solution.
√(3x+1) = 1 + √(7x+8)
square both sides
3x+1 = 1 + 2√(7x+8) + 7x+8
-4x -8 = 2√(7x+8)
-2x-4 = √7x+8)
square both sides again
4x^2 + 16x + 16 = 7x+8
4x^2 + 9x + 8 = 0
x = (-9 ± √-47)/8
no real solution.
Answered by
Kristi
I'm sorry I wrote the equation wrong 3ã(x+1)-ã(7x+8)=1
Answered by
Kristi
square roots to replace the a's
Answered by
Reiny
so
3√(x+1) - √(7x+8) = 1 , clearly x≥-1
3√(x+1) = 1 + √(7x+8)
square both sides
9(x+1) = 1 + 2√(7x+8) + 7x+8
9x+9 = 1 + 2√(7x+8) + 7x+8
2x = 2√(7x+8)
square again
4x^2= 4(7x+8)
4x^2 - 28x - 32 = 0
x^2 - 7x - 8 = 0
(x-8)(x+1) = 0
x=8 or x=-1
since we squared, all answers must be checked
if x = 8
LS = 3√9 - √(7(8) + 8)
= 9 - 8
= RS
if x = -1
LS = 3√0 - √(-7)+8))
= 0-1
≠ RS
So x = 8
3√(x+1) - √(7x+8) = 1 , clearly x≥-1
3√(x+1) = 1 + √(7x+8)
square both sides
9(x+1) = 1 + 2√(7x+8) + 7x+8
9x+9 = 1 + 2√(7x+8) + 7x+8
2x = 2√(7x+8)
square again
4x^2= 4(7x+8)
4x^2 - 28x - 32 = 0
x^2 - 7x - 8 = 0
(x-8)(x+1) = 0
x=8 or x=-1
since we squared, all answers must be checked
if x = 8
LS = 3√9 - √(7(8) + 8)
= 9 - 8
= RS
if x = -1
LS = 3√0 - √(-7)+8))
= 0-1
≠ RS
So x = 8
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