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In order to solve the question, we need to know one of the shortcut multiplication formulas:
We apply the formula twice:
Now we add the two together:
Declares the given expression as a sum
\( (7b-3x)^2 \)
That's not how squaring binomials works! When you square (x-2), you're multiplying (x-2) × (x-2), which gives three terms: x², the middle term -4x, and 4. You can't ignore the middle term!
Think of it as "First² - 2×First×Last + Last²". For (x-3)²: x² - 2(x)(3) + 3² = x² - 6x + 9. The middle term is always twice the product of the two terms!
Group by powers of x: collect all x² terms (1x² + 1x² = 2x²), all x terms (-4x - 6x = -10x), and all constants (4 + 9 = 13).
Absolutely! FOIL gives the same result: (x-2)(x-2) = x² - 2x - 2x + 4 = x² - 4x + 4. Both methods work, but the formula (x-y)² = x² - 2xy + y² is often faster.
Pick a simple value like x = 0 and substitute into both the original expression (0-2)² + (0-3)² = 4 + 9 = 13 and your answer 2(0)² - 10(0) + 13 = 13. They should match!
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