Answer:
42. 29°
43. 3x³ +2x² -3x +10
44. 20a² +68a
Explanation:
42. The right-angle corner tells you the two marked angles are complementary — they sum to 90°.
(-3x +20)° + (-2x +55)° = 90°
-5x +75 = 90 . . . . . . . . . . collect terms, divide by °
-5x = 15 . . . . . . . . . . . . . . . subtract 75
x = -3 . . . . . divide by the coefficient of x
The angle of interest is (-3x+20)°. Filling in the found value for x, we have ...
(-3·(-3) +20)° = 29° = m∠BDC
___
43. The distributive property is useful for multiplying polynomials.
(x +2)(3x² -4x +5) = x(3x² -4x +5) +2(3x² -4x +5)
= 3x³ -4x² +5x +6x² -8x +10 . . . . . eliminate parentheses
= 3x³ +2x² -3x +10
___
44. Area is the product of length and width, so this becomes a problem in multiplying polynomials.
area = (5a +17)(4a) = 20a² +68a . . . . area in square feet