Negatives Inside
Part of the Numbers & Operations section of Coddy's Pre-Algebra journey. Lesson 47 of 60.
Negative numbers follow the same order as every other number; each step just brings its sign rule along. Take -2 × (5 - 9). Parentheses first: 5 - 9 is -4. Then the product: -2 × (-4) is 8, because two negatives multiply to a positive.
When a line holds several products, work them all out before the sums. In 6 × (-3) - 4 × (-5) the products are -18 and -20, so the line is -18 - (-20). Subtracting a negative is adding its opposite, so you can write that straight away as -18 + 20, which is 2.
Doing the products first matters. Going left to right instead would subtract 4 from -18 and then multiply the result by -5, which gives 110, nowhere near 2.
Challenge
Work out (-3) × 4 - 5 × (-2). Work out both products first.
Try it yourself
Simplify the expression
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Numbers & Operations
1Working on the Board
Your First AnswerType the Next LineOne Line at a TimeDots and BarsFriendly ProductsRecap: Board Work4Adding Integers
Adding Two NegativesDifferent SignsZero PairsAdding Several IntegersRecap: Adding Integers2Order of Operations
Multiply Before AddingLeft to RightParentheses FirstBrackets Inside BracketsThe Fraction Bar GroupsRecap: Order of Operations5Subtracting Integers
Add the OppositeSubtracting a NegativePlus and Minus in a RowDistance Between NumbersRecap: Subtracting Integers6Multiplying and Dividing
Negative Times PositiveTwo NegativesCounting the NegativesDividing IntegersZero in DivisionRecap: Multiply and Divide9Putting It All Together
Powers Before ProductsNegatives InsideNegative Bases in SumsEverything at OnceRecap: The Full Order