Adding & subtracting polynomials?

Question

ok, i was given this example by my teacher & a bunch of problems to go along with it, but i have no clue wut he did or how he got the numbers or the + & - signs...

(7x^2-8)-(-3x^2+1)=(7x^2-8)+(3x^2-1)=1...

i hate math...

Answer 1

well he just took the negative as a common factor

-(3x^2-1) and turned +1 into -1 bec (negative*negative= positive)

so it became (7x^2-8)+(3x^2-1)

Answer 2

Hi, Sneaky!

Here's how you do it:

(7x^2-8 )- (-3x^2+1)

Step1: Remove the symbol of grouping, in this case, the parentheses.

(7x^2-8 ) - (-3x^2+1)

Note: if the parentheses is preceded by a + (no sign still means +), you may remove it without changing the sign of the terms inside. If the parentheses is preceded by a -, remove it but make sure to change the sign of each of the terms inside. Thus,

= 7x^2 - 8 + 3x^2 - 1

Step2: Collect similar terms. Similar terms have the same literal parts, unless they are constants. When collecting, just add (or subtract, as the case may be) the coefficients or the constants.Thus,

= 7x^2 + 3x^2 - 8 - 1

= 10x^2 - 9 Answer

Note: the coefficients of x^2 are +7 and +3; when added, the sum is 10; so, 10x^2.

-8 - 1 is the same as -8 + -1, which is of course equal to -9.

Math is lovely, and lovable, believe me.