3x ² -3xy - 5x + 5y

=(3x²-3xy)-(5x-5y)

=3x(x-y)-5(x-y)

=(x-y)(3x-5)

b) x ² + 4x – 45

=x²+9x-5x-45

=(x²+9x)-(5x+45)

=x(x-9)-5(x-9)

=(x-9)(x-5)

\(13\dfrac{1}{3}:1\dfrac{1}{3}=20:\left(2x-1\right)\)

=>13=20:(2x-1)

=>20:(2x-1)=13

=>2x-1=\(\dfrac{20}{13}\)

=>2x=\(\dfrac{33}{13}\)

=>x=\(\dfrac{33}{26}\)

A= -(x-\(\dfrac{1}{3}\))²-25

do -(x-\(\dfrac{1}{3}\))²\(\le0\forall x\)

=>-(x-\(\dfrac{1}{3}\) )²-25\(\le-25\)

=>MaxA=-25

khi x-\(\dfrac{1}{3}\)=0

=>x=\(\dfrac{1}{3}\)

3^x+ 4×3^x+1=351

=>3^x+4.3^x.3=351

=>3^x(1+12)=351

=>3^x.13=351

=>3^x=27

=>3^x=3³

=>x=3

(x²-y²)(x-y)

=(x-y)(x+y)(x-y)

=(x-y)²(x+y)

Em bé ko có răng! Tick nha!!

\\(x^3+x^2-x+2\\)

=x³+2x²-x²-2x+x+2

=(x³+2x²)-(x2+2x)+(x+2)

=x²(x+2)-x(x+2)+(x+2)

=(x+2)(x²-x+1)

b. \\(x^3-6x^2-x+30\\)

=x³+2x²-8x²-16x+15x+30

=(x³+2x²)-(8x²+16x)+(15x+30x)

=x²(x+2)-8x(x+2)+15(x+2)

=(x+2)(x²-8x+15)

=(x+2)(x²-5x-3x+15)

=(x+2)[(x²-5x)-(3x-15)]

=(x+2)[x(x-5)-3(x-5)]

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

đơn giản