Solving inequalities - GMAT Quantitative

To solve this problem we need to isolate our variable .

We do this by subtracting from both sides and subtracting from both sides as follows:

Now by dividing by 3 we get our solution.

or

There are two integers between 2.25 and 4.5, which are 3 and 4.

Like any other equation, we solve the inequality by first grouping like terms. Grouping the terms on the left side of the equation and the constants on the right side of the equation, we have:

7< 2x-3 <15

3 is added to each side to isolate the x term:

10< 2x <18

Then each side is divided by 2 to find the range of x:

5< x <9

The only integers that are between 5 and 9 are 6, 7, and 8.

The answer is 3 integers.

5 < 3x + 10 leq 16

Subtract 10: -5 < 3x leq 6

Divide by 3: -5/3 < x leq 2

We must carefully check the endpoints. is greater than and cannot equal , yet CAN equal 2. Therefore should have a parentheses around it, and 2 should have a bracket: is in

Subtract 3 from both sides:

Divide both sides by :

Remember: when dividing by a negative number, reverse the inequality sign!

Now we need to decide if our numbers should have parentheses or brackets. is strictly greater than , so should have a parentheses around it. Since there is no upper limit here, is in (-2, infty ).

Note: Infinity should ALWAYS have a parentheses around it, NEVER a bracket.

$(x-1)^{2}$ must be positive, except when . When , $(x-1)^{2}$=0.

Then we know that the inequality is only satisfied when , and xneq 1. Therefore , which in interval notation is (-infty , -4).

Note: Infinity must always have parentheses, not brackets. has a parentheses around it instead of a bracket because is less than , not less than or equal to .

The roots we need to look at are

:

Try

, so

does not satisfy the inequality.

:

Try

so does satisfy the inequality.

:

Try

so does not satisfy the inequality.

:

Try .

so satisfies the inequality.

Therefore the answer is and .

We want to see what values of x satisfy the equation. $x^{2}$-4 is under a radical, so it must be positive.

$x^{2}$-4geq 0

$x^{2}$geq 4

xgeq 2, xleq -2

When multiplying or dividing by a negative number on both sides of an inequality, the direction of the inequality changes.

Subtract 7:

Divide by -1. Don't forget to switch the direction of the inequality signs since we're dividing by a negative number:

Simplify:

or in interval form, .

The lowest value n can take is 6.

Our first step is to simplify the expression. We need to remember our order of operations or PEMDAS.

First distribute the 0.4 to the binomial.

Now distribute the 10 to the binomial.

Now multiply 0.6 by 5

Remember to flip the sign of the inequation when multiplying or dividing by a negative number.

220 will make the expression negative.

To solve this problem all we need to do is solve for :

Solve for in both inequalities:

(1)

Subtract 9 from each side of the inequality:

Then, divide by . Remember to switch the direction of the sign from "less than or equal to" to "greater than or equal to."

(2)

Add to both sides of the inequality:

Subtract 7 from each side of the inequality:

Divide each side of the inequality by 3:

From solving both inequalities, we find such that:

Only is in that interval .

and are less than 1.33, so they are not in the interval.

and are more than 2, so they are not in the interval.

The inequality that is presented in the problem is:

Start by moving your variables to one side of the inequality and all other numbers to the other side:

Divide both sides of the equation by . Remember to flip the direction of the inequality's sign since you are dividing by a negative number!

Reduce:

The only answer choice with a value greater than is .

First let's solve each of the inequalities:

Don't forget to flip the direction of the sign when dividing by a negative number:

is the correct answer. is an integer greater than 3 and is greater than 9. Therefore, the sum of and is greater than 12.

is not true. and are two positive integers as is greater than 3 and is greater than 9. The sum of two positive integers cannot be a negative number.

is not true. and are two positive integers as is greater than 3 and is greater than 9. The division of two positive numbers is positive and therefore cannot be less than 0.

is not true. is greater than 3 and is greater than 9. The product of and cannot be less than 3.

is not true. and are positive. Therefore, the product of and is negative and cannot be greater than 0.

First, we solve both inequalities:

If satisfies both inequalities, then is greater than 5 AND is greater than 11. Therefore is greater than 11.

is the correct answer.

We start by simplifying our inequality like any other equation:

Now we must remember that when we divide by a negative, the inequality is flipped, so we obtain:

Solving inequalities is very similar to solving equations, but we need to remember an important rule:

If we multiply or divide by a negative number, we must switch the direction of the inequality. So a "greater than" sign will become a "less than" sign and vice versa.

We are given

Start by moving the and the over:

Simplify to get the following:

Then, we will divide both sides of the equation by . Remember to switch the direction of the inequality sign!

So,