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Class 7 (Marathi)

Course: Class 7 (Marathi)>Unit 6

Lesson 3: Addition and subtraction of algebraic expressions

Subtracting polynomials

Sal simplifies (16x+14) - (3x² + x - 9). Created by Sal Khan and Monterey Institute for Technology and Education.

Want to join the conversation?

• at why are we adding negative 1 times 3x
• because you are going to have to distribute the negative one to all of the 3x square + x - 9
• why it is multiplyed by -1?
• Because negative sign is equal to -1 and he is distributing it.
• why do we have to include the negative 1 in this problem, but not in others where you subtract polynomials.
• I believe the -1 is simply to emphasize the fact that you need to distribute the negative sign throughout the polynomial.

Either way, at the end (when done correctly), putting a negative 1 or a negative sign can be used interchangably.
• I know Sal Khan doesn't mention this, but how would we go about solving for x in (16x+14) - (3x² + x - 9)?
• What you've written is just an expression, not an equation. You can't solve for x because there's nothing to solve.

You can simplify the expression, but it will still have different values for different values of x.
• using division algorithm divide 6x^3+13x^2+x-2 by 2x+1 and find the quotient and remainder
• Just divide! The quotient would be 3x^2 + 5x - 2 and there is no remainder.
Hope this helps! If you have any questions or need help, please ask! :)
• What is the Foil Method?
• AKA First Outside Inside Last
• I thought the answer would be 15x+23-3x^2. Am I still correct?
• what do you do if the same variable has different exponents? for example: D^2 - D^3
• The same variables with different exponents can just be thought of as separate terms. D²-D³ does not simplify further, and it is not equal to D⁻¹.