Answer:
x=1+2√2 or x=1−2√2
Step-by-step explanation:
Let's solve your equation step-by-step.
3x2−6x=21
Step 1: Since the coefficient of 3x^2 is 3, divide both sides by 3.
3x2−6x
3
=
21
3
x2−2x=7
Step 2: The coefficient of -2x is -2. Let b=-2.
Then we need to add (b/2)^2=1 to both sides to complete the square.
Add 1 to both sides.
x2−2x+1=7+1
x2−2x+1=8
Step 3: Factor left side.
(x−1)2=8
Step 4: Take square root.
x−1=±√8
Step 5: Add 1 to both sides.
x−1+1=1±√8
x=1±√8
x=1+2√2 or x=1−2√2
Answer:
D
Step-by-step explanation:
step 2 : x + 3 = 0 and x - 5 = 0 ← correct
step 3
x = 3 and x = - 5 ← error made here with signs, correct statement should be
x + 3 = 0 ⇒ x = - 3
x - 5 = 0 ⇒ x = 5
To get from 8.4 to 10 in multiplication, we need to multiply 8.4 by 10/8.4
That means that if we multiply 30 by 10/8.4 we get the answer
which is 35,714
The same with the other
8.4 times 100/30 = 28
