Mathematical problems. The problem of merging the same kind of items after the addition and subtraction of integral Is it OK to calculate like the square of 9x + 6x - the square of 3x + 2x = (9x-3x) + (the square of 6x + the square of 2x)?

Mathematical problems. The problem of merging the same kind of items after the addition and subtraction of integral Is it OK to calculate like the square of 9x + 6x - the square of 3x + 2x = (9x-3x) + (the square of 6x + the square of 2x)?

Your first step is right. Your second step is wrong. 9x-3x = (9-3) x = 6x 6x ^ 2 + 2x ^ 2 = (6 + 2) x ^ 2 = 8x ^ 2
Thank you!

What's the rule for merging like items?

When the coefficients of the same kind are added together, the result is taken as the coefficient, and the letter and the exponent of the letter remain unchanged

The rule of merging similar terms

Similar items: the same letters, the same number of letters are the same!
Merge similar items: find out similar items, letters do not change, coefficients add up!