Question

tính

(3x+5) (2x-7)

(2x-1)(x²-5x+3)

(a+b) (a+b)

(a-b) (a-b)

Answer 1

\(\left(3x+5\right)\left(2x-7\right)=6x^2-21x+10-35=6x^2-11x-35\)\(\left(2x-1\right)\left(x^2-5x+3\right)=2x^3-10x^2+6x-x^2+6x-3=2x^3-11x^2+12x-3\)

\(\left(a+b\right)\left(a+b\right)=\left(a+b\right)^2=a^2+2ab+b^2\)

\(\left(a-b\right)\left(a-b\right)=\left(a-b\right)^2=a^2-2ab+b^2\)

Answer 2

\(\left(3x+5\right)\left(2x-7\right)=6x^2-21x+10x-35=6x^2-11x-35\)

\(\left(2x-1\right)\left(x^2-5x+3\right)=2x^3-10x^2+6x-x^2+5x-3=2x^3-11x^2+11x-3\)

\(\left(a+b\right)\left(a+b\right)=\left(a+b\right)^2=a^2+2ab+b^2\)

\(\left(a-b\right)\left(a-b\right)=\left(a-b\right)^2=a^2-2ab+b^2\)

Answer 3

a, \(\left(3x+5\right)\left(2x-7\right)=3x\left(2x-7\right)+5\left(2x-7\right)\)

\(=3x\left(2x\right)+3x\left(-7\right)+5\left(2x-7\right)\)

\(=3x\left(2x\right)+3x\left(-7\right)+\left(5.2x-7.5\right)\)

\(=6x^2-21x+10x-35\)

\(=6x^2-11x-35\)

c, \(\left(a+b\right)\left(a+b\right)=\left(a+b\right)^2=a^2+2ab+b^2\)

d, \(\left(a-b\right)\left(a-b\right)=\left(a-b\right)^2=a^2-2ab+b^2\)