Solve the Expression: 2a+b Where a=10 and b=-3

Q: Why does +(-3) become -3?

When you add a negative number, it's the same as subtracting the positive version. So $ +(-3) = -3 $ follows the rule that adding negative equals subtraction.

Q: Do I multiply first or add first?

Always follow order of operations (PEMDAS)! Multiplication comes before addition, so calculate $ 2 \times 10 = 20 $ first, then $ 20 + (-3) = 17 $.

Q: What if I substitute the wrong values?

Double-check which variable equals which number! In this problem, a = 10 and b = -3. Mix them up and you'll get completely wrong answers.

Q: How do I handle the negative sign when substituting?

Keep the negative sign with the number! When b = -3, write it as $ +(-3) $ in your expression, then simplify to $ -3 $.

Q: Can I check my answer somehow?

Yes! Substitute your values again: $ 2(10) + (-3) $. If you get 17 again, you're correct. If not, redo the calculation step by step.

Variable Substitution with Negative Numbers

Solve the following expression:

$2a+b=$

If $a=10,b=-3$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:07 Let's begin by setting up and calculating.

00:10 We'll substitute the right values as given in the problem. Remember to use parentheses.

00:33 A positive times a negative number always results in a negative.

00:38 We'll solve it step by step, following the order of operations.

00:42 And that's how we find the solution to this question!

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Solve the following expression:

$2a+b=$

If $a=10,b=-3$

Step-by-step solution

Let's place the numbers in the formula:

$2\times10+(-3)=$

Let's remember the rule:

$+(-x)=-x$

Let's write the exercise in the appropriate form:

$2\times10-3=$

Let's solve the multiplication exercise:

$2\times10=20$

Now we get the exercise:

$20-3=$

Therefore, the answer is:

$17$

Final Answer

$17$

Key Points to Remember

Essential concepts to master this topic

Substitution Rule: Replace each variable with its given numerical value
Technique: Calculate $2 \times 10 = 20$ then add $+(-3) = -3$
Check: Verify $2(10) + (-3) = 20 - 3 = 17$ ✓

Common Mistakes

Avoid these frequent errors

Adding the negative sign incorrectly
Don't write $2 \times 10 + 3 = 23$ ! This ignores the negative sign on b = -3 and gives the wrong result. Always keep the negative sign: $+(-3) = -3$ which becomes subtraction.

Practice Quiz

Test your knowledge with interactive questions

What will be the sign of the result of the next exercise?

$(-2)\cdot(-4)=$

FAQ

Everything you need to know about this question

Why does +(-3) become -3?

When you add a negative number, it's the same as subtracting the positive version. So $+(-3) = -3$ follows the rule that adding negative equals subtraction.

Do I multiply first or add first?

Always follow order of operations (PEMDAS)! Multiplication comes before addition, so calculate $2 \times 10 = 20$ first, then $20 + (-3) = 17$ .

What if I substitute the wrong values?

Double-check which variable equals which number! In this problem, a = 10 and b = -3. Mix them up and you'll get completely wrong answers.

How do I handle the negative sign when substituting?

Keep the negative sign with the number! When b = -3, write it as $+(-3)$ in your expression, then simplify to $-3$ .

Can I check my answer somehow?

Yes! Substitute your values again: $2(10) + (-3)$ . If you get 17 again, you're correct. If not, redo the calculation step by step.

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