Do a proportion. X/7/8=1/1/2. 7/8 x 1= 7/8. Now do 7/8 divided by 1/2. To do this multiply 7/8 by the reciprocal of 1/2 which is 2/1. 7 x 2= 14 and 8 x 1=8. Improper fraction is 14/8. It is 1 6/8 as a mixed number which is simplified to 1 3/4. Answer is 1 3/4
Answer:
(x - 5)² = 41
Step-by-step explanation:
* Lets revise the completing square form
- the form x² ± bx + c is a completing square if it can be put in the form
(x ± h)² , where b = 2h and c = h²
# The completing square is x² ± bx + c = (x ± h)²
# Remember c must be positive because it is = h²
* Lets use this form to solve the problem
∵ x² - 10x = 16
- Lets equate 2h by -10
∵ 2h = -10 ⇒ divide both sides by 2
∴ h = -5
∴ h² = (-5)² = 25
∵ c = h²
∴ c = 25
- The completing square is x² - 10x + 25
∵ The equation is x² - 10x = 16
- We will add 25 and subtract 25 to the equation to make the
completing square without change the terms of the equation
∴ x² - 10x + 25 - 25 = 16
∴ (x² - 10x + 25) - 25 = 16 ⇒ add 25 to both sides
∴ (x² - 10x + 25) = 41
* Use the rule of the completing square above
- Let (x² - 10x + 25) = (x - 5)²
∴ (x - 5)² = 41
Answer:
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3x+15=0
<=> 3x=-15
<=> x= -15/3
<=> x= -5
Vậy nghiệm của đa thức 3x+15 là -5
