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

Ответ:

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