Find the greatest common divisor for 21 and 10

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth

To factor 4x2-25, you can first rewrite the expression as: