(15-4i)(6-3i) = a +bi in the equation above, a and b are real numbers and i = square root of -1. what is the value of a? i need on how to solve this! ? you!

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.

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.

Find the arc length of the semicircle. 7the grade