Bonsoir,
a. 3(2t + 5)²
= 3( 4t² +20t +25)
= 12t² + 60t +75
C. (8t+ 1)² – (3t)²
= 64t² +16t +1 -9t²
= 55t² +16t +1
b. (x + 1)(7 – 3x)²
=(x+1) ( 49 -42x +9x² )
= 49x -42x² +9x³ +49 -42x +9x²
= 9x³ -33x² +7x +49
d. -3(u-1)²
= -3( u² -2u +1)
= -3u² +6u -3