Đáp án:
Giải thích các bước giải:
$\left(3x+2y\right)^2\:-5\left(x-3y\right)^2$
$=9x^2+12xy+4y^2-5\left(x^2-6xy+9y^2\right)$
$=9x^2+12xy+4y^2-5x^2+30xy-45y^2$
$=4x^2+42xy-41y^2$
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$\left(3x-5\right)^2\:-2\left(x+4\right)\left(x-4\right)+\left(2x+1\right)^2$
$=9x^2-30x+25-2\left(x+4\right)\left(x-4\right)+\left(2x+1\right)^2$
$=9x^2-30x+25-2\left(x+4\right)\left(x-4\right)+4x^2+4x+1$
$=9x^2-30x+25-2x^2+32+4x^2+4x+1$
$=11x^2-26x+58$
