please tell me fast I will mark brainliest
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1) ab - bc + (bc - ca)
= ab - bc + bc - ca
= ab - ca
= a(b - c)
2) 8 - 9xy + 3x² - 5x - (3x² - 2x + 5xy - 7)
= 8 - 9xy + 3x² - 5x - 3x² + 2x - 5xy + 7
= 8 + 7 - 9xy - 5xy + 3x² - 3x² - 5x + 2x
= 15 - 14xy - 3x
3) (x + 7) (x + 7)
= (x + 7)²
(a + b)² = a² + b² + 2ab
(x + 7)² = x² + 7² + 2×x×7
= x² + 49 + 14x
4) (3x +1) (3x - 8)
= 3x× 3x - 3x × 8 + 3x - 8
= 9x² - 24x + 3x - 8
= 9x² - 21x - 8
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Answer:
Step-by-step explanation:
(ab-bc) + (bc-ca)
ab-bc+bc-ca= ab-ca
(3x²-2x+5xy-7) -(8-9xy+3x²-5x)
3x²-2x+5xy-7-8+9xy-3x²+5x
Collect the like terms
3x²-3x²+5xy+9xy+5x-2x-7-8
=14xy+3x-15
(x+7)(x+7)
x(x+7)+7(x+7)
=x²+7x+7x+49=x²+14x+49
(3x+1)(3x-8)
3x(3x-8)+1(3x-8)
9x²-24x+3x-8
=9x²-21x-8
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