Ask Dr. Math

Middle School Archive

Browse Middle School Algebra
Stars indicate particularly interesting answers or good places to begin browsing.

Selected answers to common questions:
    Direct and indirect variation.
    Inequalities and negative numbers.
    Positive/negative integer rules.
    Solving simple linear equations.

---

Simplifying Expressions [01/27/1997]

How do you simplify 3x - 2y - x -3y?

Simplifying Expressions [11/24/1997]

Solve: 2x - ( 3 - x ) = x - 7 .

Simplifying Mixed Algebraic Expressions [05/08/1998]

Simplifying fractions such as 2x - (x+y)/y and 4 - 3/(y-1) - 1/(y+1).

Simplifying Polynomials [4/26/1996]

How do you simplify polynomials?

Simplifying Using the Distributive Property [09/07/99]

How do you simplify an expression like 12(c+3d+4e) + 2(2c+d+6e)?

Simplifying with Cube Roots [01/22/1997]

Simplify: cube root(3) / [cube root(6) + cube root(3)]

Simultaneous Equations [8/25/1996]

Ten percent of the reds were added to twenty percent of the blues, and the total was 24...

Simultaneous Equations [08/10/1997]

A, B, and C can finish a job in 6 days... In how many days can each man working alone do the job?

Simultaneous Equations [07/01/2002]

A man has a total of 20 dimes and quarters. If the dimes were quarters and the quarters were dimes he would have 90 cents more than he has now. How many of each coin does he have?

Six Chickens, Five Minutes [01/09/2003]

If 1 and 1/2 chickens lay 1 and 1/2 eggs in 1 and 1/2 minutes, how many eggs will 6 chickens lay in 5 minutes?

Slope and (x, y) Intercept [02/19/1999]

Does slope depend on (x, y) intercept or does (x, y) intercept depend on slope?

Slope-Intercept Formula [06/05/2001]

Why does y = mx + b have to be that way?

Solutions to Equations [01/16/1997]

How do you make a table of values of x and y that make the equation 3/4y = -x true?

Solution Using Verbal Argument and Model [02/06/2002]

Mr. Li has fewer than 200 sweets. He wants to give each pupil in his class an equal number of sweets. If he gives each pupil 2 sweets, he will have 70 sweets left over; if 4, he will need 10 more sweets. How many pupils are there in the class? How many sweets does Mr. Li have?

Solve 2x + 3 = 10 [09/17/2001]

I don't understand what to do to simplify the problem.

Solve for g... [04/08/1997]

I understand -3x+5x+4 = -6 to solve for x, but I don't understand g+.04g+60 = 8796.

Solve Using Elimination [01/24/2001]

Solve by using elimination, and check solutions: x+6y=20, x+2y=12.

Solving a Fraction Problem Using Common Sense [03/21/2004]

When the gun sounded, only two-fifths of the racers began to run. If 460 racers began to run, how many racers were there in all? Can you show me how to figure out what a fraction is without knowing the total number?

Solving a Linear Equation in One Variable [02/27/1998]

Solve for q: -13 - q - 9 = 5q - 9 - q.

Solving a Math Poem [05/24/2000]

Take five times which plus half of what, and make the square of what you've got...

Solving a Mixture Problem Intuitively and with Algebra [07/06/2007]

There are 7 litres of turpentine in a mixture of 21 litres of water and turpentine. How many litres of turpentine must be added to make a mixture of 75% turpentine?

Solving an Algebraic Equation [12/21/1995]

If x = 2y = 3z = 1,then what is x(y-z)squared + y(z-x)squared + z(x- y)squared?

Solving an Equation with two Variables [11/20/1995]

The problem is n + n + 5 = 25. How do I do this? It has two variables.

Solving a Rational Inequality [11/15/2004]

How do you solve a rational inequality like (x-1)/(x+3) < 3?

Solving a System of Three Equations in Three Variables [06/23/2007]

How can I find values of x, y, and z that make all three of these equations true: x + y + z = 10, x - 2y + z = -2, and x - y - z = -12?

Solving a Typical Rate-Time-Distance Problem [09/02/2005]

A look at how to use algebra to solve problems involving rates, times, and distances. The problem in this example centers around walking and running at two different rates for a total of 3 hours.

Solving Equations [9/3/1995]

If n=x^2+y then how can you work out x if you know n and y, and work out y knowing n and x?

Solving Equations [3/23/1996]

A student has a number of 'word problems' that require solving equations.

Solving Equations [01/15/1998]

Please help me solve these equations: x2+y = 31; y2+x = 41.

Solving Equations for Variables [02/03/2002]

How do you solve the following equation for (M) and then (m)? k = M-m/ 1+Mm.

Solving Equations that Equal Zero [02/26/1997]

How do you solve an equation like (5x+10)(7x-2) = 0?

Solving Equations to Find Profit [8/10/1996]

You buy A and B for 40,000 Won; sell A for a 0.3 percent and B at a 0.2 percent discount. You profit 5000 Won - what was the original price of A?

Solving Equations with Square Roots [03/28/2003]

When solving x + 1 = sqrt(x + 3), we can square both sides then solve the equation; however, we get an extra solution that doesn't work. Why?

Solving for b [05/10/2000]

When solving 10 + 2*sqrt(b) = 0 we get b = 25, but when we insert 25 into the equation, we end up with 20 = 0. What are we doing wrong?

Solving for X [01/13/1997]

Solve for x in 3(x*x)-2x+2 = 2/(3(x*x)-2x+1).

Solving for x [1/23/1996]

I need help on this problem: x/x+4 = x+1/x+8

Solving for x with Fractions [9/9/1996]

How do I solve this: 5/2 = 3/2 - x ?

Solving Inequalities [08/31/1998]

How do you graph these inequalities...?

Solving Inequalities [12/10/1996]

How do you solve 6(m-4)-2(m+2) is less than 7(m-4)-6 ?

Solving Inequalities with Absolute Values [09/16/1998]

Can you explain two different ways to solve inequalities with absolute values?

Page: [<prev]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 [next>]