8B Factorising Trinomials

Factorise

x² - 8x + 15

• (x + 5) ( x + 3)

• (x - 5) (x - 3)

• (x + 15) (x - 1)

• (x - 7) (x - 8)

Factorise

r² -16r + 60

• (r - 15)(r + 4)

• (r - 6)(r + 10)

• (r - 6)(r - 10)

• (r +30)(r - 2)

Factorise

x² + 9x - 36

• (x + 12)(x - 3)

• (x + 9)(x - 4)

• (x - 12)(x + 3)

• (x - 9)(x - 4)

Factorise

a² - a - 12

• (a - 4)(a + 3)

• (a + 6)(a - 4)

• (a - 6)(a + 4)

• (a + 4)(a - 3)

If

 $p^2+12p-45=\left(p+a\right)\left(p+b\right)$  then  $a+b=?$  

• 12

• -12

• 45

• -45

If $n^2-15n-34=\left(n+a\right)\left(n+b\right)$ 

then  $a\times b=?$  

• 15

• -15

• 34

• -34

 $x^2+5x-66=\left(x\ ⋆\ 11\right)\left(x\ ⋆\ 6\right)$  

What signs should replace the stars?

• + +

• + -

• - +

• - -

 $x^2-13x+42\ =\left(x\ ⋆\ 6\right)\left(x\ ⋆\ 7\right)$  

What signs should replace the stars?

• + +

• + -

• - +

• - -