Answer:
(g) [tex](5x-2)(3x+2)[/tex]
(h) [tex](16a-18)(a-2)[/tex]
(i) [tex]3(21n^2+42n+16)[/tex]
Step-by-step explanation:
To factor a quadratic in the form [tex]ax^2+bx+c[/tex]
- Find 2 two numbers ([tex]d[/tex] and [tex]e[/tex]) that multiply to [tex]ac[/tex] and sum to [tex]b[/tex]
- Rewrite [tex]b[/tex] as the sum of these 2 numbers: [tex]d + e = b[/tex]
- Factorize the first two terms and the last two terms separately, then factor out the comment term.
Question (g)
[tex]15x^2+4x-4[/tex]
[tex]\implies ac=15 \cdot -4=-60[/tex]
[tex]\implies d+e=4[/tex]
Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
Therefore, the two numbers (d and e) that multiply to -60 and sum to 4 are:
10 and -6
Rewrite [tex]4x[/tex] as [tex]+10x-6x[/tex]:
[tex]\implies 15x^2+10x-6x-4[/tex]
Factories first two terms and last two terms separately:
[tex]\implies 5x(3x+2)-2(3x+2)[/tex]
Factor out common term [tex](3x+2)[/tex]:
[tex]\implies (5x-2)(3x+2)[/tex]
Question (h)
[tex]16a^2-50a+36[/tex]
[tex]\implies ac=16 \cdot 36=576[/tex]
[tex]\implies d+e=-50[/tex]
Factors of 576: 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 48, 64, 72, 96, 144, 192, 288, 576
Therefore, the two numbers that multiply to 576 and sum to -50 are:
-32 and -18
Rewrite [tex]-50a[/tex] as [tex]-32a-18a[/tex]:
[tex]\implies 16a^2-32a-18a+36[/tex]
Factories first two terms and last two terms separately:
[tex]\implies 16a(a-2)-18(a-2)[/tex]
Factor out common term [tex](a-2)[/tex]:
[tex]\implies (16a-18)(a-2)[/tex]
Question (i)
[tex]63n^2+126n+48[/tex]
Factor out common term 3:
[tex]\implies 3(21n^2+42n+16)[/tex]
This cannot be factored any further.
