Question

What is the sum of `3x^2 + x + 8` and `x^2 - 9`?

Answer 1

`4x^2 + x - 1`

Explanation:

To obtain the sum of : `3x^2 + x + 8 + x^2 - 9`

`color(blue)" collect like terms "`

like terms are terms with the 'same' variable and power.

example : `5x^2 " and " 8x^2 " are like terms "`

but `6x^2 " and " 3x " are not "`

In the above expression `3x^2 " and " x^2 " are like terms "`
and can be collected by adding their coefficients ( the number values in front of them).

the x term has no other terms with only x in them, and numbers are summed in the normal way.

`rArr 3x^2+x+8+x^2-9 = 4x^2 + x - 1`