Răspuns :
a) 16y² - 25( y + 4)² = [ 4y - 5( y + 4)] [ 4y + 5( y + 4)] =
= ( 4y - 5y - 20)( 4y + 5y + 20)
= ( - y - 20)( 9y + 20), folosesti formula
a² - b² = ( a - b)( a + b)
c) 64x³ + 1 = 4³x³ + 1³
= ( 4x + 1)( 4²x² - 4x·1 + 1²)
= ( 4x + 1)( 16x² - 4x + 1), folosesti formula de calcul prescurtat
a³ + b³ = ( a + b)( a² - ab + b²)
= ( 4y - 5y - 20)( 4y + 5y + 20)
= ( - y - 20)( 9y + 20), folosesti formula
a² - b² = ( a - b)( a + b)
c) 64x³ + 1 = 4³x³ + 1³
= ( 4x + 1)( 4²x² - 4x·1 + 1²)
= ( 4x + 1)( 16x² - 4x + 1), folosesti formula de calcul prescurtat
a³ + b³ = ( a + b)( a² - ab + b²)
a)16Y²-25(Y+4)² =
=[4Y+5(Y+4)][4Y-5(Y+4)] =
=(4Y+5Y+20)(-Y-20) =
=(9Y+20)(-Y-20) =
c)64X³+1=(4x+1)(16x²-4x+1)
=[4Y+5(Y+4)][4Y-5(Y+4)] =
=(4Y+5Y+20)(-Y-20) =
=(9Y+20)(-Y-20) =
c)64X³+1=(4x+1)(16x²-4x+1)