Khan Academy Algebra

Which of the following is a logical reason we use letters in algebra?

• We wanted to make math harder.

• There were enough numerals, so we had to start borrowing letters.

• Someone got confused and thought zero looked like an O and started using letters.

• We needed symbols to represent unknown numbers.

The word Algebra comes from an Arabic word roughly translated as _________________.

• balancing

• restoration/completion

• solving

• mathematics

_____________ are used to represent unknown numbers.

Greek mathematician Diophantus is sometimes credited as the father of algebra. Who did the video say is arguably really the father of Algebra?

• Pythagoras

• Euclid

• al-Kwarizmi

• Aristotle

Solve: -2(2x - 8) + 8x = 12

• x = 1

• x = -1

• x = 4

• x = -4

What is the first step to solve this equation?

-2(x - 3) + 5x = 72

• Combine Like Terms

• Distribute

• Change the variables with the constants

• Throw it away and go to Starbucks

Solve: 2(x + 2) = -8

• x = -4

• x = 1,234,567

• x = 6

• x = -6

What is the second step needed to solve this equation:

4(x - 5) - 3x + 4 = 250

• Solve for x

• Add all the constants with the coefficients

• Combine Like Terms

• Distribute

Solve the following equation:

25 = -5(x - 2)

• x = -3

• x = 3

• x = 5

• x = -5

Solve: 91 = 7(x + 8)

• x = -5

• x = 90

• x = 5

• x = 1