Question

3х÷4х-4+5х÷7-7х,

2b÷2b+c-4b²÷4b²+4bc+c²

Answer 1

$frac{3x}{4x-4}+frac{5x}{7-7x}=frac{3x}{4(x-1)}+frac{5x}{7(1-x)}=$$frac{3x}{4(x-1)}-frac{5x}{7(x-1)}=frac{21x-20x}{28(x-1)}=frac{x}{28(x-1)}$

 

$frac{2b}{2b+c}-frac{4b^{2}}{4b^{2}+4bc+c}=frac{2b}{2b+c}-frac{4b^{2}}{(2b+c)^{2}}=$$frac{4b^{2}+2bc-4b^{2}}{(2b+c)^{2}}=frac{2bc}{(2b+c)^{2}}$