Question

Tính giá trị biểu thức

a) A= \(100^2+200.50+50^2\)

b) B= \(127^2+146.127+73^2\)

c) C= \(\left(x-3\right)^2-\left(x+4\right)\left(x-4\right)\)tại x =100

d) D= \(\left(2x-3y\right)\left(4x^2+6xy+9y^2\right)\)tại x = \(\frac{-1}{2}\)và y = \(\frac{-1}{3}\)

Answer 1

a, \(A=\left(100+50\right)^2=22500\)

b, \(B=\left(127+73\right)^2=40000\)

c, \(C=-6x+25\)Thay x = 100 ta có : 

\(C=-6.100+25=-600+25=-575\)

Answer 2

\(A=100^2+200.50+50^2\)

\(=100^2+2.100.5+50^2\)

\(=\left(100+50\right)^2=150^2\)

\(B=127^2+146.127+73^2\)

\(=127^2+2.73.127+73^2\)

\(=\left(127+73\right)^2=200^2\)

Answer 3

\(C=\left(x-3\right)^2-\left(x+4\right)\left(x-4\right)\)

\(=x^2-6x+9-x^2+16=25-6x\)

\(=25-600=-575\)

\(D=\left(2x-3y\right)\left(4x^2+6xy+9^2\right)=8x^3-27y^3\)

bạn thế vô là xong