. Solve using the square root property:(x + 3)^2 = 49?
回答 (9)
2008-12-26 1:24 am
✔ 最佳答案
√(x+3)²=±√49x+3=±7
x=-10 or 4
2008-12-26 5:11 am
(x + 3)² = 49
x² + 3x + 3x + 9 = 49
x² + 6x = 40
x² + 3x = 40 + 3²
x² + 3x = 40 + 9
(x + 3)² = 49
x + 3 = 7
x = 7 - 3, x = 4
x = - 7 - 3, x = - 10
Answer: x = 4, - 10
Proof (x = 4):
(4 + 3)² = 49
7² = 49
49 = 49
Proof (x = - 10):
(- 10 + 3)² = 49
- 7² = 49
49 = 49
x² + 3x + 3x + 9 = 49
x² + 6x = 40
x² + 3x = 40 + 3²
x² + 3x = 40 + 9
(x + 3)² = 49
x + 3 = 7
x = 7 - 3, x = 4
x = - 7 - 3, x = - 10
Answer: x = 4, - 10
Proof (x = 4):
(4 + 3)² = 49
7² = 49
49 = 49
Proof (x = - 10):
(- 10 + 3)² = 49
- 7² = 49
49 = 49
2016-11-06 11:58 pm
x=4 first you're taking the sq. root of the two aspects to cancel the sq.. then which will supply you x+3=7 subtract 3 from the two aspects and you get x=4. you may plug it decrease back in to make constructive it works
2008-12-26 1:50 am
x^2+6x+9=49
x^2+6x-40=0
(x+10)(x-4)=0
x=-10 or 4
x^2+6x-40=0
(x+10)(x-4)=0
x=-10 or 4
2008-12-26 1:44 am
(x + 3)^2 = 49
x + 3 = ±√49
x + 3 = ±7
x + 3 = 7
x = 7 - 3
x = 4
x + 3 = -7
x = -7 - 3
x = -10
∴ x = -10 , 4
x + 3 = ±√49
x + 3 = ±7
x + 3 = 7
x = 7 - 3
x = 4
x + 3 = -7
x = -7 - 3
x = -10
∴ x = -10 , 4
2008-12-26 1:24 am
(x + 3)^2 = 49
x+3 = 7
or
x+3 = -7
There are two answers, because 7 x 7= 49, but (-7) x (-7) = 49. Therefore there are two solutions, 7 and -7.
Now simplify the two expressions.
x+3 = 7
x=4
x+3= -7
x= -11
x+3 = 7
or
x+3 = -7
There are two answers, because 7 x 7= 49, but (-7) x (-7) = 49. Therefore there are two solutions, 7 and -7.
Now simplify the two expressions.
x+3 = 7
x=4
x+3= -7
x= -11
2008-12-26 1:23 am
(x + 3)² = 49
take square root of both sides.
±(x + 3) = ±7
two possibilities
x + 3 = +7
x + 3 = –7
x = 4, –10
other method
(x + 3)² = 49
x² + 6x + 9 – 49 = 0
x² + 6x – 40 = 0
(x + 10)(x – 4) = 0
x = –10, 4
.
take square root of both sides.
±(x + 3) = ±7
two possibilities
x + 3 = +7
x + 3 = –7
x = 4, –10
other method
(x + 3)² = 49
x² + 6x + 9 – 49 = 0
x² + 6x – 40 = 0
(x + 10)(x – 4) = 0
x = –10, 4
.
2008-12-26 1:19 am
x+3 = +/- 7--->x = -10, 4
2008-12-26 4:41 pm
square both sides of the equation:
You get x+3 = 7. Therefore, x = 4
You get x+3 = 7. Therefore, x = 4
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