First translate the English phrase "Four times the sum of a number and 15 is at least 120" into a mathematical inequality.
"Four times..." means we're multiplying something by 4.
"... the sum of a number and 15..." means we're adding an unknown and 15 and then multiplying the result by 4.
"... is at least 120" means when we substitute the unknown for a value, in order for that value to be in the solution set, it can only be less than or equal to 120.
So, the resulting inequality is 4(x + 15) ≤ 120.
Simplify the inequality.
4(x + 15) ≤ 120 4x + 60 ≤ 120 <-- Using the distributive property 4x ≤ 60 <-- Subtract both sides by 60 x ≤ 15 <-- Divide both sides by 4
Now that we have the inequality in a simplified form, we can easily see that in order to be in the solution set, the variable x can be no bigger than 15.
In interval notation it would look something like this:
[15, ∞)
In set builder notation it would look something like this:
{x | x ∈ R, x ≤ 15}
It is read as "the set of all x, such that x is a member of the real numbers and x is less than or equal to 15".
Solving 4=2x is using the division property because in order to get the last portion of that answer u have to divide both sides by 2x to get x by itself For example 4=2x to get x by itself you have to divide both sides by 2x And your final answer would be x is equal to 2 (x=2)
Answer: A reflection across the x-axis keeps the x-coordinates the same but flips the signs of the y-coordinates. So, it should be the opposite for a reflection across the y-axis. The y-coordinates remain the same, but the signs of the x-coordinates change.
