12th grade is last year in high school if I remember correctly.
would that be right?
equation is:
3b^2 + 4x - 10
plus: -b^2 + 5x + 6
equals: 2b^2 + 9x - 4
you add all the like terms together.
3b^2 + (-b^2) = 3b^2 - b^2 = 2b^2
4x + 5x = 9x
-10 + 6 = -4
put them all together and you get:
2b^2 + 9x - 4
when you add numbers together with different signs, you simply subtract the smaller number from the larger number and give the sign of the larger number to the result.
that's why -10 + 6 = -4.
I subtracted 6 from 10 and got 4. since the larger number of 10 was negative, I made the sign of the result negative.
3b^2 - b^2 = 2b^2 as follows:
3b^2 is the same as b^2 + b^2 + b^2
b^2 + b^2 + b^2 - b^2 = b^2 + b^2 = 2 * b^2
same with 5x + 4x
5*x = x + x + x + x + x
4*x = x + x + x + x
add them together and you get:
x + x + x + x + x + x + x + x + x = 9 * x.