1) 7x(x-4)-x(6-x) = 7x·x+7x·(-4)-x·6-x·(-x) = 7x²-28x-6x+x² = 8x²-34x
2) 5ab(4a+3b)-10a²(2b-4) = 5ab·4a+5ab·3b-10a²·2b-10a²·(-4) = 20a²b+15ab²-20a²b+40a² = 40a²+15ab²
3) xy(2x-11y)-x(xy+14y²) = xy·2x+xy·(-11y)-x·xy-x·14y² = 2x²y-11xy²-x²y-14xy² = x²y-25xy²
4) 5c³(4c-3)-2c²(8c²-12) = 5c³·4c+5c³·(-3)-2c²·(8c²)-2c²·(-12) = 20c⁴-15c³-16c⁴+24c² = 4c⁴-15c³+24c²
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1) 7x(x-4)-x(6-x) = 7x·x+7x·(-4)-x·6-x·(-x) = 7x²-28x-6x+x² = 8x²-34x
2) 5ab(4a+3b)-10a²(2b-4) = 5ab·4a+5ab·3b-10a²·2b-10a²·(-4) = 20a²b+15ab²-20a²b+40a² = 40a²+15ab²
3) xy(2x-11y)-x(xy+14y²) = xy·2x+xy·(-11y)-x·xy-x·14y² = 2x²y-11xy²-x²y-14xy² = x²y-25xy²
4) 5c³(4c-3)-2c²(8c²-12) = 5c³·4c+5c³·(-3)-2c²·(8c²)-2c²·(-12) = 20c⁴-15c³-16c⁴+24c² = 4c⁴-15c³+24c²