Here is one way to solve for x.
Step 1) 2x^2-7=9
Step 2) 2x^2-7+7=9+7
Step 3) 2x^2=16
Step 4) (2x^2)/2=16/2
Step 5) x^2=8
Step 6) sqrt(x^2)=sqrt(8)
Step 7) |x|=sqrt(8)
Step 8) x=sqrt(8) or x=-sqrt(8)
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Below are explanations/reasons to each of the steps above.
Step 1) Original equation
Step 2) Add 7 to both sides
Step 3) Combine like terms
Step 4) Divide both sides by 2
Step 5) Simplify
Step 6) Apply the square root to both sides. The notation "sqrt" is shorthand for "square root"
Step 7) Use the rule that sqrt(x^2) = |x| for all real numbers x
Step 8) Use the rule that if |x| = k then x = k or x = -k for some fixed number k.
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The two solutions are
x = sqrt(8) or x = -sqrt(8)
Answer: 28 dots
Step-by-step explanation: In this pattern,
we can see the the first figure is just 1 dot.
The second figure has a new row on the bottom with 2 dots.
The third figure has a new row on the bottom with 3 dots
and the fourth figure has a new row on the bottom with 4 dots.
So continuing with this pattern,
the next figure will have a new row with 5 dots,
the next will have a new row with 6 dots,
and the next will have a new row with 7 dots.
So in the 7th picture, we will have 7 + 6 + 5 + 4 + 3 + 2 + 1 dots.
This simplifies to 28 dots.
Take a look below.