A researcher studies the rate of progress of a chemical reaction. The researcher fixes the temperature and pressure, varies the amount of catalyst used over a range of quantities, and observes the resulting reaction rate in each case. Which statement BEST describes why the investigation is an experimental study?

There is more than one independent variable to study.

The researcher manipulates at least one independent variable.

It is possible to get data with a range of values of an independent variable.

There is a cause-effect relation between the independent and dependent variables.

Use addition and subtraction to simplify the following polynomials. a. add polynomials: (3 – 4x + 8x^2) + (–6 + 2x – 5x^2) step 1: rewrite the polynomials without the parentheses. step 2: write the polynomial in descending order and use parentheses around like terms. step 3: add the like terms identified in step 2 to simplify the polynomial. b. subtract polynomials: (3x – 5 – 7x^2) – (–2 + 6x^2 – 5x) step 1: rewrite the polynomials without the parentheses. remember to multiply each term in the second parentheses by –1. show your work. step 2: write the polynomial in descending order and use parentheses around like terms. step 3: add the like terms identified in step 2 to simplify the polynomial.

55 bridesmaids want to make 325 325 decorations for a wedding. each decoration takes about 212 2 1 2 minutes to make. which response gives the best estimate for the amount of time each bridesmaid will spend making decorations?

Write 5(6x+4)-2(5x-2) in the form a(bx+c) where a,b and c integers and a> 1