Let, f(x)=x5−20x3+50x+2
Now differentiating the function f(x) with respect to x we get,
f′(x)=5x4−60x2+50
⇒f′(x)=5(x4−12x2+10)
Now equating f′(x)=0 we get,
x4−12x2+10=0
⇒x2=212±144−40
⇒x2=6±26
⇒x2≈11.1,0.9
⇒x≈±3.31,±0.95
Now finding the nature of function at integer value near by above value we get,
f(0)=2,f(1)>0,f(2)<0,f(-1)<0&f(-2)>0
Now plotting the graph by observing above values, we get,

Hence, it will cross x−axis 5 times.