Factor each polynomial by grouping?

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1) 10ab-6b+35a-21

2) 6st+9t-10s-15

3) 15-5m^2-3r^2+m^2r^2
Best Answer
1) 10ab - 6b + 35a - 21
(10ab - 6b) + (35a - 21)
2b(5a - 3) + 7(5a - 3)
(5a - 3)(2b + 7) <== factored

2) 6st + 9t - 10s - 15
(6st + 9t) - (10s + 15) <== note the - is factored out on the right two terms
3t(2s + 3) - 5(2s + 3)
(2s + 3)(3t - 5) <== factored

3) 15 - 5m^2 - 3r^2 + m^2 r^2
(15 - 5m^2) - (3r^2 - m^2 r^2)
5(3 - m^2) - r^2(3 - m^2)
(3 - m^2)(5 - r^2) <== factored over rational numbers

if you need to find linear terms:
(sqrt(3) - m)(sqrt(3) + m)(sqrt(5) - r)(sqrt(5) + r)

(but we would normally stop at factors over the rational numbers)
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  • Mika answered 4 years ago
    1.) (2b+7)(5a-3)
    2.) (3t-5)(2s+3)
    3.) (5-r^2)(3-m^2)
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  • MK answered 4 years ago
    1 and 2 stayy the samme idkk about 3
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