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To solve this equation, add 3x to both side. You will get
2x + 15 + 3x = -3x + 3x,
5x + 15 = 0.
Now subtract 15 from both sides. You will get
5x + 15 - 15 = 0 - 15
5x = - 15.
Now divide both sides by 5. You will get
x = -15/5 = -3.
ANSWER. x = -3 is the solution.
CHECK. Left side value is 2x + 15 = 2*(-3) + 15 = -6 + 15 = 9.
Right side value is -3x = -3*(-3) = 9.
Left side value is equal to the right side value; so, the solution is correct.
Solved.
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The algorithm of solution is THIS:
- collect the terms with x in the left side of the equation;
- collect the constant terms in the right side;
- combine the terms with x in the left side;
- combine the constant terms in the right side;
- you will get an equation of the form ax = b.
- If coefficient "a" is not zero, divide both sides of the equation by "a".
- You will get x = . It is the solution to given equation.
- When the solution is obtained, make a check.
To do it, compute separately left side of the equation and right side.
If the computed values coincide, the solution is correct.
It is how students solve simple and simplest linear equations.
What to do and what happens if coefficient "a" is zero, they learn later.
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If you want to see many samples on solving simple and simplest linear equations, look into the lesson
- HOW TO solve a linear equation
in this site.
Consider this lesson as your textbook, handbook, tutorial and (free of charge) home teacher.
Happy learning (!)