1. leave....won't

2. sells....won't have

3. come...won't let

4. does...will be

5. won't attend.....don't invite

(x - 2)(x + 3)

= \(x^{2} + 3 x - 2 x - 6\)

= \(x^2+x-6\)

= 2

10 x 10 = 100

1. population

2. visit

3. clock

4. pollution

5. streets

6. best

7. five

8. world

a) \(\left(4x-2\right)\left(5x-1\right)=0\)

\(\rArr4x-2=0\) hoặc \(5x-1=0\)

+) Với \(4x-2=0\) \(\rarr\) \(x=\frac12\)

+) Với \(5x-1=0\rarr x=\frac15\)

Vậy \(x=\frac12;x=\frac15\)

b) \(\frac{3 x \left(\right. x + 2 \left.\right)}{\left(\right. x - 2 \left.\right) \left(\right. x + 2 \left.\right)} + \frac{4 x \left(\right. x - 2 \left.\right)}{\left(\right. x - 2 \left.\right) \left(\right. x + 2 \left.\right)} = \frac{- 5 x^{2} - 2 x}{\left(\right. x - 2 \left.\right) \left(\right. x + 2 \left.\right)}\)

\(3 x \left(\right. x + 2 \left.\right) + 4 x \left(\right. x - 2 \left.\right) = - 5 x^{2} - 2 x\)

\(3 x^{2} + 6 x + 4 x^{2} - 8 x = - 5 x^{2} - 2 x\)

\(7 x^{2} - 2 x = - 5 x^{2} - 2 x\)

\(7 x^{2} - 2 x + 5 x^{2} + 2 x = 0\)

\(12 x^{2} = 0\)

\(x^{2} = 0\)

\(x = 0\)

Vậy x = 0

(14 + 2x) : 5 = 2,4

(14 + 2x) = 2,4 x 5

(14 + 2x) =12

2x = 12 - 14

2x = -2

x = -2 : 2

x = -1

Vậy x= -1

304?

\(= x^{4} + x^{3} y + x^{2} y^{2} + x y^{3} - x^{3} y - x^{2} y^{2} - x y^{3} - y^{4}\)

\(= x^{4} - y^{4}\)

Vậy, \(\left(\right. x - y \left.\right) \left(\right. x^{3} + x^{2} y + x y^{2} + y^{3} \left.\right) = x^{4} - y^{4}\) (đpcm)

\(= x^{5} - x^{4} y + x^{3} y^{2} - x^{2} y^{3} + x y^{4} + x^{4} y - x^{3} y^{2} + x^{2} y^{3} - x y^{4} + y^{5}\)

\(= x^{5} + y^{5}\)

Vậy, \(\left(\right. x + y \left.\right) \left(\right. x^{4} - x^{3} y + x^{2} y^{2} - x y^{3} + y^{4} \left.\right) = x^{5} + y^{5}\) (đpcm)