a)
a=4 i b = 1/2
3ab - \frac{5a}{2b}=3*4*\frac{1}{2}-\frac{5*4}{2*\frac{1}{2}}=6-20=-14
II sposób
napierw upraszczam wyrażenie
3ab - \frac{5a}{2b}=\frac{3ab*2b-5a}{2b}=\frac{a(6b^2-5)}{2b}=\frac{4(6*\frac{1}{4}-5)}{2*\frac{1}{2}}=4(1,5-5)=4*(-3,5)=-14
b)
m=5 , n=-4
-5(m-n)(3+n)=-5[5-(-4)][(3+(-4)]=-5(5+4)(3-4)=
-5*9*(-1)=45
c)
y=-1 , z=-2
\frac{4y-3z}{z^2}=\frac{4*(-1)-3*(-2)}{(-2)^2}=\frac{-4+6}{4}=\frac{2}{4}=\frac{1}{2}
d)
x=2\sqrt2
\frac{1- 2x^2}{2}=\frac{1-2*(2\sqrt2)^2}{2}=\frac{1-2*4*2}{2}=\frac{1-16}{2}=-\frac{15}{2}=-7\frac{1}{2}