Question

Используя формулу (a + b)2 = a2 + 2ab + b2, найди значения квадратов: 12^2 = + 40 + = ;

15^2 = + 100 + = ;

16^2 = + 120 + = ;

21^2 = + 40 + = .

Answer 1

$12^2=(10+2)^2=10^2+2\cdot 2\cdot 10+2^2=100+\boxed {40}+4=144\\\\15^2=(10+5)^2=100+2\cdot 10\cdot 5+25=100+\boxed{100}+25=225\\\\16^2=(10+6)^2=100+2\cdot 10\cdot 6+36=100+\boxed{120}+36=256\\\\21^2=(20+1)^2=400+2\cdot 20\cdot 1+1=400+\boxed{40}+1=441$