Question

1) Tính nhanh

a)174^2-74^2

b)115^2-30.115+15^2

c) 49^2+102*49+51^2

3)

a) x^2-12xy+36y^2

b) 25x^2-49y^2

c)27x^3 +27x^2+9x+1

Answer 1

1) Tính nhanh:

a/ \(174^2-74^2=\left(174+74\right)\left(174-74\right)=248.100=24800\)

b/ \(115^2-30.115+15^2=115^2-2.15.115+15^2=\left(115-15\right)^2=100^2\)

\(=10000\)

c/ \(49^2+102.49+51^2=49^2+2.51.49+51^2=\left(49+51\right)^2=100^2\)

\(=10000\)

Answer 2

3)

a) \(x^2-12y+36y^2\)

\(=\left(x-6y\right)^2\)

b)\(25x^2-49y^2=\left(5x-7y\right)\left(5x+7y\right)\)

c) \(27x^3+27x^2+9x+1=\left(3x+1\right)^3\)